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THE 


APPLIED   A:NAT0MY 


I 


OF   THE 


NERVOUS  SYSTEM, 


BEING    A    STUDY    OF    THIS   PORTION   OF  THE  HUMAN  BODY 

FROM  A  STANDPOINT  OF  ITS  GENERAL  INTEREST  AND 

PRACTICAL  UTILITY,  DESIGNED  FOR  USE  AS  A 

TEXT-BOOK  AND  A  WORK  OF  REFERENCE, 


BY 


I 


AMBKOSE  L.  KANNEY,  A.  M.,  M.  D. 


JUNCT   PROFESSOR  OF   ANATOMY   AND    LATE   LECTITRKR  ON  THE   DISEASES   OP  THE  GENITO-TIRINAEY 
ORGANS     AND     ON     MINOR    SURGERY    IN     THE    MEDICAL   DEPARTMENT   OF  THE    UNIVERSITY    OP 
THE    CITY   OF    NEW    YORK  ;     LATE    SURGEON    TO   THE    NORTHERN    AND    NORTHWESTERN 

dispensaries;  resident  fellow  of  the  new  york  academy  OF  medi- 
cine; MEMBER  OF  THE  MEDICAL  SOCIETY  OF  THE  COUNTY  OF  NEW 
YORK;   AUTHOR  OF   A   '"PRACTICAL  TREATISE  ON   SU^C^ICAL 
,      PIAGNOPJe^"    'VTHP,S'-S8DK'inALS''©P  ^^AWMY.^'^ETC. 


wiTd  ifm^i.ousl22ips,f^Ah(XNis^ 


"The  greatest  thing  a  human  soul  ever  does  in  this  world  is  to  see  something,  and  tell  what  he  saw  in 
a  plain  way.  Hundreds  of  people  can  talk  for  one  that  can  think,  but  thousands  can  think  tor  one  who 
can  see.    To  see  clearly  is  paetry,  prophecy,  and  religion  all  in  one." — John  KusIin. 


NEW  YORK: 
D.    APPLETON    AND    COMPANY, 

1,  3,   AND   5   BOND   STREET. 

1881. 


% 


COPTBIGHT  BY 

D.  APPLETON  AND  COMPANY. 

1881. 


,.,?,•;■ 


TO 

THE   FACULTY 
OF   THE   MEDICAL   DEPARTMENT 

OF   THE 

UNIVERSITY     OF     THE     CITY     OF    NEW     YORK, 

TJXDER   THE    GUIDANCE   OF    SOME    OF   WHOM 

I    PURSUED    MY. EARLY    MEDICAL    STUDIES, 

AND    TO   WHOSE    INDUSTRY   AND   TALENT 

IS   DUE   MUCH    OF   THE   SUCCESS 

WHICH    HAS    CROWNED   THEIR    EFFORTS   AS   INSTRUCTORS, 

THIS    VOLUME 

IS   RESPECTFULLY   DEDICATED 

BY  THE  AUTHOR.     " 


u^d 


PEEFACE 


This  volume  comprises  a  course  of  lectures  wliicli  were 
delivered  by  me  before  the  students  of  tlie  Medical  Depart- 
ment of  tlie  University  of  tlie  City  of  New  York  during 
the  mnter  of  1880  and  1881.  They  are  presented  to  the 
reading  public,  with  few  alterations,  as  they  were  originally 
reported  for  some  of  the  medical  journals,  and  for  the 
private  use  of  the  author.  The  same  colloquial  style  in 
which  they  were  delivered  has  been  retained,  since  it  is 
believed  that  it  will  thus  better  fill  the  requirements  of  a 
text-book.  I  am  well  aware  that  the  highest  type  of  lit- 
erary composition  is  not  of  this  conversational  character, 
and  that  it  may  be  to  some  readers  a  drawback  rather  than 
an  attractive  feature  in  the  volume ;  but  the  fact  is  also 
recognized  that  the  best  style,  theoretically,  is  not  always 
the  clearest  and  the  most  forcible,  and  that  successful 
teachers  have  often  to  sacrifice  beauty  of  rhetoric  in  order 
to  impart  their  knowledge. 

I  have  departed  somewhat  from  the  custom  of  anatom- 
ical authors  in  making  diagrammatic  illustrations — ^which 
it  is  my  habit  to  draw  upon  the  black-board  before  my 
classes,  in  order  to  make  the  listener  use  the  eye  as  well  as 
the  intelligence  as  a  means  of  gaining  information — a  prom- 


vi  PREFACE. 

inent  feature  of  this  volume.  I  have  found,  for  some  years, 
that  the  drawmg  of  illustrations  of  this  character  before 
the  eyes  of  the  student  gave  a  much  clearer  perception 
of  some  obscure  points  than  words  could  effect,  and  had 
a  great  advantage  in  this  respect  over  the  most  elaborate 
and  skillfully  executed  plates.  I  have,  therefore,  incor- 
porated many  of  my  own  designing,  and  some  others  which 
have  been  culled  from  different  sources  and  modified  to 
suit  the  demand  of  the  moment.  I  have,  in  some  instances, 
allowed  the  text  to  follow  and  explain  these  diagrams,  as 
if  the  lecture  were  in  actual  progress,  rather  than  to  trust 
the  descriptive  text  of  the  cuts  alone  to  interpret  their 
meaning. 

The  liberality  of  the  publishers  has  enabled  me  to  fur- 
ther ornament  the  work  with  the  beautiful  cuts  of  Sap- 
pey  and  Hii'schfeld,  some  of  which,  to  my  knowledge,  have 
never  appeared  in  any  American  work,  while  I  am  indebted 
to  my  friend  Professor  Austin  Flint,  Jr.,  for  some,  culled 
from  the  same  authors,  which  have  appeared  in  his  work 
upon  physiology,  and  to  my  colleague  and  friend  Professor 
William  A.  Hammond  for  some  of  the  admirable  photo- 
graphs and  woodcuts  in  his  elaborate  treatise  on  nervous 
diseases.  I  desire  also  to  express  my  indebtedness  to  my 
friend  Professor  E.  C.  Seguin  for  some  late  monogi'aphs 
and  some  excellent  diagrams,  and  to  the  works  of  Charcot, 
Ferrier,  Brown-Sequard,  Kosenthal,  Hammond,  Foster,  Hil- 
ton, Flint,  and  others,  as  well  as  to  the  authors  of  such 
valuable  monographs  as  those  of  Turck,  Hughlings-Jack- 
son,  Vulpian,  Pitres,  Duret,  Dodds,  Nothnagel,  Duchenne, 
Lockhart  Clarke,  Flechsig,  and  Erb,  for  the  valuable  as- 
sistance which  I  have  derived  from  their  labors.  It  has 
been  my  intention,  as  far  as  possible  without  disfiguring 
the  text,  to  give  all  credit  to  those  authors  who  have  a 


PREFACE.  vii 


just  claim  to  priority,  where  the  originality  of  any  matter 
is  discussed,  and  to  acknowledge  my  indebtedness  to  authors 
for  extracts  in  foot-notes  scattered  throughout  the  volume. 

The  rapid  strides  which  are  being  made  in  the  inter- 
pretation of  the  symptoms  of  nervous  diseases  and  the 
introduction  of  many  new  terms  which  must  embarrass  the 
reader  of  late  treatises,  unless  he  be  educated  up  to  the 
present  standard  of  knowledge  in  this  Held  of  medicine, 
seem  to  the  author  a  reasonable  ground  for  belief  that  there 
is  a  demand  for  a  volume  which  shall  fit  the  practitioner 
and  student  to  pursue  his  studies  in  this  special  line  with- 
out embarrassment,  if  not  with  increased  interest. 

I  have  endeavored  not  to  lose  sight  of  the  fact  that 
the  basis  of  the  work  was  an  anatomical  one,  and  that, 
while  the  clinical  points  could  be  explained  chiefly  by  anat- 
omy, the  treatment  of  nervous  diseases  had  no  place  in  the 
volume.  For  the  reason,  also,  that  the  aim  of  the  work 
is  of  a  practical  character,  much  detail  of  a  purely  de- 
scriptive kind  has  been  deemed  unimportant  in  some  in- 
stances ;  while,  again,  facts  which  are  too  often  slighted  in 
descriptive  treatises  have  been  here  given  w^th  unusual 
detail,  as  they  seemed  to  me  to  suggest  points  of  inter- 
est which  had  been  overlooked  or  intentionally  omitted 
by  others. 

It  is  not  to  be  expected  that  many  points  stated  in  the 
physiology,  symptomatology,  or  even  in  the  anatomy,  will 
not  be  open  to  discussion,  and,  possibly,  to  contradiction. 
It  is  almost  impossible,  to-day,  for  any  two  disputants  upon 
nervous  affections  or  nervous  physiology  to  fail  to  find 
support  for  either  side  in  the  literature  of  the  subject; 
but  the  statements  which  this  volume  contains  will,  it  is 
to  be  hoped,  receive  the  concurrence  of  those  most  ad- 
vanced in  this  line  of  study. 


viii  PREFACE. 

Witli  what  merits  or  demerits  the  volume  may  possess, 
I  intrust  it  to  the  public,  conscious  that  an  effort  to  clear 
up  a  field  made  obscure  by  visionary  theories  and  endless 
speculation  can  not  but  contain  some  ground  to  which  ex- 
ception may  be  taken.  To  what  extent  it  will  supply  the 
place  of  a  guide  in  this — the  labyrinth  of  medical  science 
— experience  alone  must  decide. 

Ambrose  L.  Rani^ey. 

New  York  City,  156  Madison  Avexue, 
April  10,  1881. 


TABLE   OF   COI^TEISTTS. 


GENERAL  mXRODUCTTON  .  .  .  .  .     1-16 

The  nervous  system  considered  as  a  whole. 

Its  component  parts. 

The  general  axioms  of  nerve  distribution. 


PART  I. 
THE  BRAIISr        .......       16-92 

Its  anatomy,  functions,  and  clinical  aspects. 
Its  general  construction. 

Its  weight,  and  that  of  its  component  parts. 
Its  rapidity  of  growth  and  alterations  with  age. 
Its  individual  ganglia. 
The  cerebrum    .......     25-54 

Its  situation  and  construction. 

Its  converging  and  commissural  fibers. 

Its  general  functions  and  special  centers. 

Centers  of  motion ;  of  speecli ;  of  vision  ;  of  hearing ;  of  touch ; 
of  smell ;  of  taste. 
The  frontal  lobe. 

Its  functions ;  motor  centers ;  white  substance. 
The  motor  area. 

Parts  of  the  cerebrum  comprised  within  it :  situation  of  the  spe- 
cial imotor  centers;    diagnosis  of  cortical  motor  paralysis; 
effects  of  irritative  lesions  of  the  motor  area. 
The  sensory  area. 

Parts  of  the  cerebrum  comprised  within  it;  effects  of  lesions 
within  it. 
The  occipital  lobe. 

Its  relation  to  vision  ;  psychical  functions. 
The  temporo -sphenoidal  lobe. 

Its  relation  to  vision;  to  ocular  movements;  to  hearing;  to  ol- 
factory sense ;  to  taste ;  to  tactile  sensation. 
The  corpus  striatum  and  optic  thalamus  .  .  .     54-58 

Situation  of  the  "basal  ganglia." 
Functions  of  the  "basal  ganglia." 


TABLE  OF  CONTENTS. 


functioxs  of  the  caudate  nucleus. 
Functions  of  the  lenticular  nucleus. 
The  corpora  quadrigemina    .....     58-59 

Their  relation  to  vision. 
Their  relation  to  ocular  movements. 
Their  relation  to  coohdination  of  movement. 
The  crura  cerebri  and  pons  Varolii  .  .  .     59-61 

Their  relation  to  coordination  of  muscular  movement. 
Their  relation  to  crossed  paralysis. 
Their  relation  to  the  sensation  of  pain. 
Their  probable  functions. 
The  cerebellum  ......     Cl-65 

Its  numerous  connections. 
Effects  of  lesions  within  its  substance. 
Cerebellar  ataxia. 
Its  relation  to  hearino  and  sight. 
The  medulla  oblongata  .....     65-68 

Its  relation  to  cranial  nerves. 
Its  physiological  centers: 

Kespiratoiy;  salivary;  vaso-niotor;  diabetic;  cardio-inhibitory ; 
for  deglutition ;  for  vomiting ;  for  movements  of  oesophagus 
and  stomach ;  for  digestive  secretions. 
Its  relations  to  coordination  of  movement. 
The  surgical  bearings  of  cerebral  topography  .  .     68-74 

Guides  to  the  fissure  of  Rolando. 
Guides  to  the  external  parieto-occipital  fissure. 
Guides  to  the  fissure  of  Sylvius. 
Guides  to  the  limits  of  the  "basal  ganglia." 
Guides  to  the  motor  centers. 
Guides  to  the  center  of  speech. 

Indications  and  contraindications  for  trephining  of  the  skull. 
The  clinical  significance  of  ansBsthesia  after  an  injury  to  the  skull ; 
of  convulsive  movements ;  of  the  Cheyne-Stokes  respiration ; 
of  "  choked   disk "   after  an   injury  ;    of  vomiting  after  an 
injury  ;   of  aphasia  after  an  injury ;   of  monoplegia  after  an 
injury. 
General   summary   of  the   anatomy    of  the   brain   and 

ITS  clinical  aspects  ....     74-92 

Summary  of  its  gross  anatomy. 

The  lobes  of  the  brain. 

The  fissures  of  the  brain. 

The  lobules  of  the  brain. 

The  gyri  of  each  lobe. 

The  clinical  subdivisions  of  the  brain. 

Symptoms  referable  to  the  base  of  the  cerebrum ;  to  the  basal 
ganglia ;  to  the  white  center  of  the  hemispheres ;  to  the  in- 
ternal capsule;  to  the  cortex  of  the  hemispheres;  to  the  cere- 
bellum. 


TABLE  OF  CONTENTS.  xi 

PAGES 

Summary  of  the  physiology  of   the  cerebral  cortex   and  the 
effects  of  lesions  involving  it. 

The  excitable  portion  (motor  area) — its  special  centers  and  their 
action;  the  frontal  convolutions;  the  parietal  convolutions; 
the  angular  gyrus  (probable  center  of  vision);  the  superior 
temporosphenoidal  gyrus  (probable  center  of  hearing) ;  the 
center  of  speech. 
Clinical  deductions  of  practical  value. 

Types  of  monoplegia  and  the  special  significance  of  each ;  con- 
vulsions of  cerebral  origin  (Jacksonian  epilepsy);  embolism 
of  middle  cerebral  artery  and  its  effects ;  clinical  significance 
of  late  rigidity  of  paralyzed  muscles ;  general  paralysis  of  the 
insane;  lesions  of  the  basal  ganglia  of  the  cerebrum;  let-ions 
of  the  internal  capsule  of  the  cerebrum ;  lesions  of  the  white 
center  of  the  hemispheres. 

PART  II. 

THE   CRANIAL  NERVES  .  .  .  .  .     93-287 

Their  anatomy,  physiology,  and  clinical  value. 
Enumeration,  from  before   backward,   as   they   escape  from 

THE    cavity    of    THE    CRANIUM. 

The  olfactory  nerve  .....     95-103 

Its  origin  and  construction. 
'    The  peculiarities  of  its  filaments. 
The  limits  of  its  distribution. 
The  physiology  of  olfaction. 
The  act  of  sneezing. 

Reflex  acts  dependent  upon  the  olfactory  nerve. 
Functions  of  olfactory  nerve  in  animals. 
Relations  of  the  sense  of  smell  to  that  of  taste. 
Clinical  points  afforded  by  the  olfactory  nerve. 

"Hyperosmia,"  its  tests  and  causes;  "anosmia,"  its  tests  and 

causes. 
The  optic  nerve        ......     103-127 

The  optic  tracts,  their  origin  and  attachments. 
The  optic  chiasm,  its  construction  and  physiology. 
Distribution  of  optic  nerve. 
Reflex  acts  excited  by  optic  nerve. 
Decussation  of  optic  fibers  and  its  physiology. 
Relations  of  the  optic  nerve  in  the  orbit. 
Anatomical  defects  of  vision  and  their  consequences. 

"Hyperopia,"  its   tests,   causes,    and  results;    "myopia,"  its 

tests,  causes,  and  results ;  "astigmatism,"  its  tests,  causes,  and 

results. 
Changes  observed  in  the  pupil. 

Dilatation,  its  causes  and  physiology ;  contraction,  its  causes 

and  physiology. 


xii  TABLE  OF  CONTENTS. 

PAGES 

Visual  sensations  and  their  modifications. 

Muscae  volitantes;  the  ''blind  spot"  of  the  retina;  insensibil- 
ity of  the  retina  after  firm  pressure. 
The  perception  of  color. 

Visual  purple  and  its  probable  functions;  rods  and  cones  of 
the  retina  ;  Young-Helinholtz  theory  of  color  vision  :  limits 
of  different  color  perceptions ;  color  blindness. 
Apparent  vision  of  objects  not  really  serx. 

Its  causes. 
Effects  of  optic  jierve  on  coordination. 

Goltz's  experiments. 
Effects  of  optic  nerve  on  the  lachrymal  apparatus. 

The  act  of  winking  the  eyelid  ;  eff'ect  of  closure  of  eyelid  upon 
the  lachrymal  canals. 
Clinical  points  afforded  by  the  optic  nerve. 

Hemianopsia,  temporal,   its  causes;    hemianopsia,   nasal,   its 
causes;  hemianopsia,  bi-nasal,  its  causes;  hemianopsia,  bi- 
temporal, its  causes;  amaurosis;  hypereBsthesia  of  the  optic 
nerve ;  amblyopia ;  atrophy  of  optic  nerve. 
The  motor  oculi  nerve       .....     127-149 
Its  origin,  course,  and  distribution. 
The  physiology  of  contraction  of  the  pupil. 
Physiological  reasons  for  the  distribution  of  the  third  nerve. 
Mechanism  of  the  dilatation  of  the  pupil. 
Movements  of  the  eyeball. 

Diagnostic  attitudes  of  the  head  in  ocular  paresis. 
Clinical  points  pertaining  to  the  third  nerve. 

Megalopsia  ormacropsia;  micropsia;  ptosis;  motor  oculi  pa- 
ralysis ;  strabismus.     Diseases  of  the  ocular  muscles :  nystag- 
mus;  iritic  spasm;  contracture;   paralysis;  tabetic  condi- 
tions; diplopia;  strabismus. 
The  trochlear  or  pathetic  nerve  .  .  .     149-151 

Its  superficial  and  deep  points  of  origin. 
Its  course  and  relations  within  the  cranium. 
Its  points  of  clinical  interest. 
The  trigeminus  nerve  .....     151-175 

Its  superficial  and  deep  points  of  origin. 
Course  of  its  sensory  and  motor  roots  within  the  cranium. 
Its  afferent  and  efferent  fibers. 
The  effects  of  section  of  the  nerve. 

On  sensation  ;  on  mastication ;  on  taste ;  on  bearing ;  on  sight ; 
on  smell. 
Clinical  points  pertaining  to  the  trigeminus  nerve. 

Neuralgia  (tic-douloureux) ;  spasm  of  the  trigeminus;  paralysis 
of  its  individual  branches. 
Diagnostic  value  of  the  trigeminus  nerve. 

Bleaching  of  the  hair ;  immobility  of  temporo-maxillary  joint ; 
furring  of  the  tongue ;  ulceration  of  the  cornea;  ulceration 


TABLE  OF  CONTENTS. 


XIU 


of  the  auditory  canal ;  earache  ;  pain  in  the  scalp ;  conjunc- 
tival distribution. 
Surgical  anatomy  of  its  maix  branches. 

Section  of  the  snpra-orbital  nerve  ;  section  of  the  supra-maxil- 
lary nerve;  section  of  the  inferior-dental  nerve. 
The  ganglia  connected  with  the  trigeminus  nerve. 

Ophthalmic,  lenticular,  or  ciliary ;  spheno-palatine  or  Meckel's; 
otic;  sub-maxillary. 
The  abducens  nerve  (motor  oculi  externus)     .  .     175-177 

Its  superficial  and  deep  points  of  origin. 
Its  relation  with  the  ophthalmic  ganglion. 
Its  clinical  relations. 
The  facial  nerve      ......     177-198 

Its  superficial  and  deep  points  of  origin. 
Its  course  and  distribution. 
Physiology  of  its  main  branches. 

Tlie  petrosal  nerves;  the  chorda  tympani  nerve;  the  "pars 
intermedia"  of  Wrisberg;  the  tympanic  branch;  the  facial 
branches ;  the  muscular  branches. 
Its  communications  with  other  parts. 

Branches  joining  the  fifth  nerve;  branch  to  the  otic  ganglion ; 
branch  to  Meckel's  ganglion ;  sympathetic  fibers ;  its  rela- 
tion to  deglutition  and  speech  ;  its  relation  to  smell ;  its  re- 
lation to  hearing ;  its  relation  to  respiration. 
Its  filaments  of  distribution. 

Physiological  relation  to  deglutition;  physiological  relation  to 
facial  expression ;  physiological  relation  to  mastication. 
Clinical  points  pertaining  to  the  nerve. 

Spasm  of  the  facial  muscles.    Bell's  paralysis  :  intra-cranial  va- 
riety ;  auditory  variety  ;  rheumatic  variety  ;  traumatic  vari- 
ety ;  syphilitic  variety  ;  diphtheritic  variety ;   facial  diplegia. 
The  auditory  nerve  .....     198-220 

Its  superficial  and  deep  points  of  origin. 

Anatomical  structure  and  peculiarities  of  its  filaments. 

Its  course  and  distribution. 

Functions  of  its  various  branches. 

The  mechanism  of  audition. 

External  ear,  its  construction  and  functions ;  middle  ear,  its  con- 
struction and  functions.     Internal  ear,  its  construction  and 
functions  :  the  semicircular  canals  ;  the  vestibule.    The  coch- 
lea :  its  scahie  ;  organ  of  Corti ;  membranes  and  ligaments. 
Clinical  points  pertaining  to  the  nerve. 

Auditory  vertigo — "  Meniere's  disease  "  ;  injuries  to  the  semi- 
circular canals.     Neuroses  of  the  auditory  nerve :  acoustic 
hyperesthesia ;  acoustic  anaesthesia. 
The  glosso-pharyngeal  nerve        .  .  .  .     220-236 

Its  superficial  and  deep  points  of  origin. 
Its  ganglionic  enlargements. 


XIV 


TABLE  OF  CONTENTS. 


Its  course  and  relations. 

Its  efferent  or  motor  fibers. 

Its  afferent  or  sensory  fibers. 

Its  fibers  of  taste. 

Effects  of  section  of  the  nerve. 

On  special  sense  of  taste  ;  on  deglutition. 

Mechanism  of  the  act  of  deglutition. 

First  period  ;  second  period  ;  third  period ;  nerves  involved ; 
importance  of  soft  palate;  the  nerve  center  for  the  act. 

Clinical  points  pertaining  to  the  nerve. 

Glosso-labio-laryngeal  paralysis — Duchenne's  disease  ;  hyper- 
geusia;  ageusia. 
The  pneumogastric  nerve  .....     236-259 

Its  superficial  and  deep  points  of  origin. 

Its  intimate  affiliation  with  the  glosso- pharyngeal  nerve. 

Its  ganglionic  enlargements. 

The  inherent  fibers  of  its  trunk. 

Its  branches  of  distribution  and  their  functions. 

The  pharyngeal  branches:  effects  on  deglutition;  effects  on 
voice.  The  laryngeal  branches:  their  relation  to  phona- 
tion ;  their  relation  to  respiration ;  their  relation  to  spinal 
accessory  nerve.  The  branches  to  alimentary  canal :  their 
relation  to  peristaltic  action;  their  relation  to  secretion. 
The  cardiac  branches :  depressor  nerve  of  heart's  action ; 
effects  of  galvanism.  Yaso-motor  fibers:  effects  on  blood- 
vessels. The  pulmonary  branches :  their  relation  to  respi- 
ration— acceleratory  fibers  ;  inhibitory  fibers. 

The  course   and   relations   of   the   nerve  on   each  side  of 

THE   body — 

"With  carotid  artery  ;  with  jugular  vein ;  with  oisophagus ;  with 
the  lungs ;  with  the  abdominal  viscera. 
Effects  of  section  of  the  pneumogastric  trunk. 

Upon  the  larynx  ;  upon  the  lungs;  upon  the  heart.    Upon  the 
digestive  tract :  stomach ;  liver ;  intestinal  canal. 
Clinical  points  pertaining  to  the  nerve. 

Pharyngeal  anaesthesia ;  pharyngeal  spasm  ;  pharyngeal  paral- 
ysis; laryngeal  spasm  (Kopp's  asthma);  "vvhooping  cough; 
aneurismal  cough  ;  pulmonary  asthma ;  pulmonary  vaso-mo- 
tor  paralysis  ;  angina  pectoris ;  cardiac  neuralgia  ;  gastrody- 
nia ;  boulimia ;  polydipsia ;  dyspeptic  vomiting ;  polyphagia. 
The  spinal  accessory  nerve  ....     259-272 

Its  superficial  and  deep  points  of  origin. 
Its  course  and  distribution. 
Its  filaments  of  communication. 
Its  relations  to  the  production  of  voice. 
The  effects  of  section  of  the  nerve — 

On  phonation ;  on  respiration  ;  on  deglutition ;  on  the  action 
of  the  heart ;  on  singing. 


TABLE  OF  CONTENTS. 


XV 


Clinical  points  pertaining  to  the  nerve. 

Tonic  spasm  of  sterno-mastoid  muscle ;  tonic  spasm  of  trape- 
zius;  clonic  spasm  of   sterno-mastoid  and  trapezius  mus- 
cles ;  salaam  convulsion  of  Nevvnham ;  unilateral  paralysis 
of  sterno-mastoid  and  trapezius  muscles ;  bilateral  paralysis 
of  sterno-mastoid  and  trapezius  muscles. 
The  hypo-glossal  nerve  (sub-lingual  nerve)     . 
Its  superficial  and  deep  points  of  origin. 
Its  course  and  distribution. 
The  descendens  noni  branch. 

Functions  of  the  nerve :  on  deglutition  ;  on  articulation. 
Clinical  points  pertaining  to  the  nerve. 

Duchenne's  disease :  abnormalities  of  speech  ;  abnormalities  of 
voice ;  impairment  of  deglutition  ;  facial  deformity ;  lingual 
tremor.     Lingual  spasm :  lingual  paralysis. 


272-286 


PART  in. 


THE  SPmAL  CORD     ...... 

Its  anatomical  construction,  functions,  and  clinical  bear- 
ings. 
Its  cervical  and  lumbar  enlargements. 
Its  fissures  and  columns. 

Its  nerves  (their  roots  and  general  construction). 
Its  membranes  and  the  cerebro-spinal  fluid. 

Their  functions  and  situation. 
Appearance  of  a  transverse  section  of  the  cord. 

Its  gray  matter ;  its  white  matter ;  its  central  canal ;  its 
commissures.  Pathological  subdivisions  of  the  cord:  col- 
umns of  Goll ;  columns  of  Burdach ;  columns  of  Tiirck ; 
fundamental  columns  ;  direct  pyramidal  columns  ;  anterior 
root  zones;  posterior  root  zones;  crossed  pyramidal  col- 
umns ;  direct  cerebellar  columns. 
Functions  of  the  spinal  cord. 
(i)   Organ  of  conduction. 

Paths  of  motor  impulses;  paths  of  sensory  impulses; 
commissural  fibers.  Fibers  of  the  spinal  cord  :  motor 
fibers  and  their  function;  sensory  fibers  and  their 
function;  commissural  fibers  and  their  function. 

(2)  Spinal  cord  as  a  nerve  center. 
Reflex  action  of  the  cord  ;  automatic  action  of  the  cord  ; 

vaso-motor  centers ;  cilio-spinal  center ;  genito-uri- 
nary  center;  tonic  action  on  muscles;  center  of  defe- 
cation ;  center  of  parturition ;  center  of  micturition ; 
center  of  erection. 

(3)  Organ  of  coordination  of  muscular  movements. 


287-352 


xvi  TABLE  OF  CONTENTS, 


Clinical  points  pertaining  to  the  spinal  cord. 

The  kinesodic  system ;  the  sesthesodic  system ;  diseases  of  its 
substance. 
Systematic  lesions  of  ^stiiesodic  system. 

(i)  Sclerosis  of  columns  of  Goll. 

{2)  Sclerosis  of  columns  of  Burdacli  (locomotor  ataxia). 
Systematic  lesions  of  kinesodic  system. 

(i)  Sclerosis  of  columns  of  TurcTc. 

(2)  Sclerosis  of  lateral  columns  (spasmodic  tabes,  tetanoid  pa- 
ralysis, spastic  spinal  paralysis). 

{3)  Amyotrophic  lateral  sclerosis  of  the  cord. 

(4)  Myelitis  of  the  anterior  horns  of  the  gray  matter  (atrophic 

spinal  paralysis). 

(5)  Polio-myelitis. 

Acute  variety;    infantile   spinal  paralysis;   non-febrile 
variety ;  chronic  variety. 
{&)  Progressive  muscular  atrophy. 
(7)  Central  myelitis. 
Non-systematic  or  "  focal  "  lesions  of  the  cord. 

Distinctions  between  systematic  and  focal  lesions ;  their  physi- 
ological effects  at  different  heights, 
(i)  Focal  lesions  of  the  upper  cervical  region. 

Symptoms  referable  to  the  phrenic  nerve ;  to  the  respira- 
tory center ;  to  the  acceleratory  center  of  the  heart ; 
to  the  pneumogastric  nerve. 
{2)  Focal  lesions  of  the  cervical  enlargement. 

Symptoms  referable  to  cilio-spinal  center;  to  the  ulnar 
nerve ;  to  the  acceleratory  center  of  the  heart ;  to  the 
vaso-motor  centers. 
{3)  Focal  lesions  of  the  mid-dorsal  region. 

Symptoms  referable  to  the  lower  limbs ;  to  the  genito- 
urinary organs;  to  the  reflex  excitability  of  the  spinal 
cord;  to  the  lateral  columns  of  the  spinal  cord;  to 
the  rectum. 

(4)  Focal  lesions  above  the  lumbar  enlargement. 

Symptoms  referable  to  reflex  excitability  of  the  spi- 
nal cord ;  to  the  genito-urinary  organs ;  to  the  rec- 
tum. 

(5)  Focal  lesions  of  the  lumbar  enlargement  of  the  spinal  cord. 

Symptoms  referable  to  the  sciatic  nerve ;    to  the  rec- 
tum. 

(6)  Focal  lesions  of  one  lateral  half  of  the  spinal  cord. 

(a)  Spinal-hemiplegia — symptoms  referable  to  the  inter- 
costal nerves ;  to  the  upper  extremity ;  to  the  lower 
extremity;  to  the  cilio-spinal  center;  to  the  vaso- 
motor centers. 

(b)  Hemi-paraplegia — symptoms  referable  to  the  trunk ; 
to  "  trophic  "  centers ;  to  increased  excitability  of  the 
spinal  cord ;  to  the  lower  limbs. 


TABLE   OF  CONTENTS. 


PART  lY. 

THE   SPINAL  NERVES  .  .  .  .  . 

Their  subdivisions  and  points  of  escape. 

The  construction  and  relative  size  of  their  roots. 

The  length  and  inclination  of  their  roots. 

General  axioms  of  nerve  distribution. 
The  upper  cervical  nerves  .... 

Table  of  their  branches  of  distribution ;  the  cervical  plexus — 
its  situation,  formation,  superficial  branches,  deep  branches, 
and  communications  with  other  nerves.  The  communicans 
noni  nerve:  its  origin  and  distribution.  The  phrenic  nerve: 
its  origin,  course,  surgical  relations,  and  physiological 
function.  Clinical  points  pertaining  to  the  upper  cervical 
nerves:  cervico-occipital  neuralgia;  diaphragmatic  neural- 
gia ;  clonic  diaphragmatic  spasm  (hiccough) ;  tonic  dia- 
phragmatic spasm  (diaphragmatic  tetanus);  and  diaphrag- 
matic paralysis. 
The  lower  cervical  nerves  .... 

Table  of  their  branches  of  distribution.  The  brachial  plexus : 
its  situation;  its  formation  and  abnormalities;  its  supra- 
clavicular branches  ;  its  infra-clavicular  branches  ;  its  surgi- 
cal relations ;  its  communications  with  other  nerves.  Nerves 
of  the  upper  extremity :  table  of  the  branches  of  the  outer 
cord  of  the  brachial  plexus;  table  of  the  branches  of  the  in- 
ner cord  of  the  brachial  plexus ;  table  of  the  branches  of  the 
posterior  cord  of  the  brachial  plexus.  The  anterior  thoracic 
nerves:  their  distribution  ;  their  clinical  aspects.  The  exter- 
nal or  musculo-cutaneoiis  nerve:  its  course  and  distribution 
to  muscles ;  its  cutaneous  distribution ;  its  relation  to  the 
"  bent  arm  "  after  venesection.  Clinical  points  afforded  by 
it:  paralysis  and  its  symptoms;  anaesthesia  of  forearm. 
The  median  nerve :  its  origin,  course,  and  distribution  ;  its 
surgical  relations;  its  cutaneous  distribution.  Clinical 
points  afforded  by  it :  median  paralysis  and  its  symptoms ; 
anfBsthesia  and  its  variations.  The  internal  and  lesser  in- 
ternal cutaneous  nerves:  their  origin,  course,  and  distribu- 
tion; relations  to  the  intercosto-humeral  nerve.  The  ulnar 
nerve  :  its  origin,  course,  and  distribution ;  its  surgical  rela- 
tions ;  its  cutaneous  distribution.  Chnical  points  afforded 
by  it:  ulnar  paralysis,  its  causes  and  symptoms;  its  relation 
to  the  surgery  of  the  elbow  joint.  The  siib-scapular  nerves: 
their  origin,  course,  and  distribution ;  their  surgical  relations ; 
their  cutaneous  distribution.  Clinical  points  afforded  by 
them :  scapular  paralysis.  The  circumjlex  nerve :  its  origin, 
course,  and  distribution ;  its  surgical  relations ;  its  cutaneous 
and  articular  branches.  Clinical  points  afforded  by  it:  cir- 
cumflex paralysis;  deltoid  atrophy.  The  musculo-spiral 
2 


XVll 


PAGES 

353-486 


362-377 


377-419 


xvm 


TABLE  OF  CONTENTS. 


nerve:  its  origin,  course,  and  distribution.  Its  terminal 
branches  (the  radial  and  interosseous  nerves) :  their  distri- 
bution to  muscles;  their  cutaneous  distribution.  Clinical 
points  afforded  by  it:  surgical  importance  of  its  peculiar 
course ;  its  relation  to  traumatic  paralysis ;  rheumatic  affec- 
tions of  the  nerve.  Lead  paralysis :  theories  as  to  its  etiol- 
ogy; its  symptoms;  its  differential  diagnosis ;  its  duration. 

The  dorsal  nerves   ...... 

The  thoracic  intercostal  nerves;  the  thoracico  ahdojninal  in- 
tercostal nertes:  their  origin,  course,  and  distribution;  their 
relation  to  the  pleura.  Clinical  points  afforded  by  them: 
significance  and  diagnostic  value  of  thoracic  pain;  signifi- 
cance of  pain  in  the  pit  of  the  stomach;  significance  of  pec- 
toral pain  ;  significance  and  course  of  pain  due  to  the  liver 
and  other  viscera.  Intercostal  neuralgia:  its  causes;  its 
symptoms ;  its  differential  diagnosis.  Neuralgia  of  the  mam- 
mary gland  (mastodynia) :  its  causes  and  symptoms;  its 
" puncta  dolorosa."  Paralysis  of  the  dorsal  nerves:  its  re- 
lations to  kyphosis ;  its  relations  to  scoliosis.  Paralysis  of 
the  extensor  muscles  of  the  lumbar  region:  its  diagnostic 
attitude;  its  differential  diagnosis. 

The  lumbar  nerves  ...... 

The  lumbar  plexus:  its  situation  and  formation;  its  chief 
branches  and  their  general  distribution.  The  ilio-hypo- 
gastric  nerve:  its  origin,  course,  and  distribution;  neuralgia 
of  the  nerve.  The  ilio-inguinal  nerve:  its  origin,  course, 
and  distribution ;  neuralgia  of  the  nerve ;  its  relation  to  tiie 
peritonaeum.  The  external  cutaneous  nerve :  its  origin,  course, 
and  distribution ;  its  relation  to  pains  referred  to  the  thigh. 
The  genito-crural  nerve :  its  origin,  course,  and  distribution. 
Clinical  points  afforded  by  it.  The  anterior  crural  nerve : 
its  origin,  course,  and  distribution;  its  physiological  func- 
tion; its  distribution  to  joints;  its  cutaneous  branches. 
Clinical  points  afforded  by  it:  its  surgical  relations ;  its  rela- 
tion to  pain  in  the  region  of  the  knee.  Spasm  of  the  quad- 
riceps extensor  muscle.  Crural  paralysis:  its  causes  and 
symptoms.  Atrophy  of  muscles  supplied  by  this  nerve. 
Crural  neuralgia:  its  causes;  its  "puncta  dolorosa";  the 
lie  contracture    of   Stromeyer."      The    olturator 


nerve:  its  origin,  course,  and  distribution;  its  distribution 
to  joints;  its  relation  to  pain  in  the  vicinity  of  the  knee;  ita 
physiological  functions.  Clinical  points  afforded  by  it: 
obturator  neuralgia;  obturator  paralysis.  The  accessory 
obturator  nerve :  its  origin,  course,  and  distribution ;  its  ab- 
normalities. 


The 


SACRAL   NERVES  . 

Their  anatomical  peculiarities, 
and  formation;  its  situation 


419-436 


457-480 


The  sacral  plexus:  its  shape 
its  branches  of  distribution. 


TABLE  OF  CONTENTS, 


XIX 


The  superior  gluteal  nerve :  its  origin,  course,  and  distribu- 
tion ;  its  physiological  function.  Clinical  points  afforded  by 
it:  peculiarities  of  its  cutaneous  distribution;  its  surgical 
relations;  gluteal  spasm;  gluteal  paralysis.  The  muscular 
Iranches  of  the  sacral  plexus:  their  distribution;  their 
physiological  functions.  The  small  sciatic  nerve:  its  origin, 
course,  and  distribution;  its  physiological  functions;  rela- 
tion of  its  perineal  branch  to  the  genital  organs.  The  pudic 
nerve:  its  origin,  course,  and  distribution;  the  inferior 
hemorrhoidal  nerve;  the  perineal  nerve;  the  dorsal  nerve 
of  the  penis.  Clinical  points  afforded  by  the  pudic  nerve : 
its  relations  to  coitus  ;  its  relations  to  micturition ;  its  rela- 
tions to  defecation;  neuralgic  affection  of  its  branches. 
The  great  sciatic  nerve:  its  origin,  course,  and  distribution; 
its  distribution  to  joints.  The  external  popliteal  nerve :  its 
course  and  branches  of  distribution.  Distribution  of  nerves 
to  the  fascia  of  the  leg.  The  internal  popliteal  nerve :  its 
course  and  branches  of  distribution.  Clinical  points  afforded 
by  the  great  sciatic  nerve  and  its  branches.  Sciatic  neuralgia 
(malum  Cotunnii) :  its  causes ;  modifications  of  its  seat ;  its 
characteristic  symptoms ;  its  "  puncta  dolorosa  " ;  its  motor 
manifestations ;  its  vaso-motor  effects.  Spasms  of  the  lower 
limb :  spasmodic  contracture  of  the  hip ;  tonic  and  clonic 
spasms  of  extensor  and  adductor  groups  of  muscles;  spasm 
of  the  anterior  muscles  of  the  leg.  Paralysis  of  the  great 
sciatic  nerve  or  its  branches:  sciatic  paralysis;  peroneal 
paralysis;  tibial  paralysis;  their  sensory  manifestations; 
their  trophic  disturbances. 


INDEX 


487-500 


LIST    OF    ILLUSTEATIONS. 


no. 
1. 

9 


4. 
5. 
C. 

r. 

8. 

9. 

10. 

11. 
12. 
13. 
U. 

15. 

16. 

ir. 

18. 
19. 

20. 
21. 


Nerve  fibers  from  the  human  subject    .  KolliTcer 

Cervical  and  thoracic  portions   of  the 

SYMPATHETIC  .  .  ...  Sappey 

Lumbar  and  sacral  portions  of  the  sym- 
pathetic    ....." 

Fibers  of  Remak  (Magnified)  .  .  Robin  . 

Mode  of  termination  of  the  motor  nerves  Itouget 

A  diagram  of  the  brain  in  profile  .  Quain 

Vertical  section  op  the  encephalon        .  Hirschfeld 

A  diagram   of   the  brain  in  transverse 

VERTICAL   SECTION  .  .  .  Balton 

Inferior  aspect  of  the  encephalon  .  Hirsclifeld 

Convolutions   of  the  internal  aspect  of 

the  hemispheres    ....  Sappey 

A   DIAGRAM  OF  THE   FIBERS  IN  THE    CEREBRUM  Le   BoTh 

A   DIAGRAM  OF  THE  CEREBRAL   CONVOLUTIONS  DaltOTl 

Structure  of  the  cerebral  convolutions  Baillarger 

A    DIAGRAM     OF    THE     SENSORY     AND     MOTOR 

TRACTS    OF   THE   BRAIN  .  .  .  Seguiu 

Side  view  of  the  special  areas  op  the 

CEREBRAL   CONVOLUTIONS      .  .  .  FetrieT 

Upper  view  of  the  special  areas  of  cere- 
bral .  convolutions  .  .  .        " 
a  diagram  showing  the  course  of  nerve 

impulses   in   THE   BRAIN        .  .  .  Dodds   . 

The  CORPORA  striata  .  .  .  Sappey 

A  DIAGRAM  TO  ILLUSTRATE  "  CROSSED  PARALY- 
SIS "  .  .  .  .  .  Hammond 

The   CEREBELLUM   AND   MEDULLA   OBLONGATA  HlTSChfeld 

Anterior  view  of  the  medulla  oblongata  Sappey 
Outline  of   the  skull  and  its  surgical 

guides         .  .  .  .  .  Topinard  and 

A   DIAGRAM    OF   THE   LOBES    AND   FISSURES    OF 

THE  CEREBRUM        ....  Fevriev 


Seguin 


PAGB 

6 

6 

8 

9 

10 

20 

21 

22 
23 

25 

27 
31 
33 

35 

39 

41 

53 
55 

60 
61 

65 

70 
76 


xxu 


LIST  OF  ILLUSTRATIONS. 


FIG. 

24.  a  diagram    of    the    cerebbum    in  longi- 

tudinal median  section  . 

25.  Lateral  view   of    the  special  areas   of 

the  cerebral  cortex 

26.  Superior  view  of  the  special  areas   of 

the  cerebral  cortex 

27.  Roots  of  the  cranial  nerves 

28.  Olfactory  ganglion  and  nerves  . 

29.  Terminal    filaments    of    the    olfactory 

NERVE  ..... 

30.  Internal    branches    of    the    olfactory 

NERVE  ..... 

31.  Optic  tracts,  commissure,  and  nerves 

32.  A  diagram    of  the  decussation    of    the 

optic  fibers  .... 

33.  A  diagram   of   the   optic   fibers   in  the 

RETINA  ..... 

34.  Relation  of  the  optic    nerve  and  oph- 

thalmic ARTERY      .... 

35.  Relation    of    the    optic    nerve    to    the 

blood-vessels,  in  the  orbit 

36.  A  diagram  of  the  defective  diameters  of 

the   EYE        ..... 

37.  Anterior  view  of  the  crystalline  lens 

38.  two  cuts  of  the  retina  and  its  elements 

39.  a  diagram  to  show  the  limits  of  color 

VISION  ..... 

40.  Lachrymal  and  Meibomian  glands 

41.  Lachrymal  apparatus 

42.  A  diagram  to  show  the  effects  of  press- 

ure on  the  optic  nerve 

43.  Distribution  of  the  third  cranial  nerve 

44.  The  ciliary  muscle,  lens,  iris,  and   cor- 

nea 4  .  .  .  . 

45.  The  ciliary  nerves  and  choroid  coat  of 

eye  ..... 

46.  The  nerves  of  the  iris 

47.  The  ciliary  nerves 

48.  A  diagram  showing  the  mechanism  of  the 

accommodation  of  vision 

49.  Muscles  of  the  eyeball 

50.  A  diagram  showing  the  axes  of  rotation 

OF    THE    EYEBALL       .... 

51.  Two     DIAGRAMS     OF     THE     ELEMENTS    OF     THE 

RETINA  ..... 

52.  Distribution    of     the     fourth     cranial 

NERVE  ..... 

53.  The   ophthalmic    division    of   the   fifth 

cranial  nerve       .... 


Dalton 
Terrier 

Hirachfeld 

(I 

KolUTcer 

Sappey 
Eirachfeld 

Flint . 

Weher  . 

Ranney 


Bahuchin 

Mailer  and  Sappey 


HirscJiberg 
Sappey 


Ranney 
Hirschfeld 


Sappey 


Ficlc. 

134 

Sappey 

136 

FkJc     . 

139 

Mailer  and  Sappey 

144 

Eirschfeld       . 

150 

(( 

15'2 

LIST  OF  ILLUSTBATIONS. 


no. 

54.  a    diagram   of  the   distribution  of  the 

fifth  cranial  nerve 

55.  The    inferior  maxillary  division  of  the 

FIFTH   cranial   NERVE 

56.  The  superior  maxillary   division  of  the 

fifth  cranial  nerve 

57.  Superficial  branches   of   the   fifth  and 

FACIAL    nerves  .... 

58.  Cutaneous  nerve  distribution  of  the  head 

59.  Distribution  of  the  sixth  cranial  nerve 

60.  The  superficial  branches    of  the  facial 

nerve  ..... 

61.  a  diagram  of  the  branches  of  the  fa- 

cial nerve  .... 

62.  Expression  of  the  face  in  "bell's  paral- 

ysis" .  .  .  .  . 

63.  a  diagram  of  the  communications  between 

the   facial   and   TRIGEMINUS   NERVES 

64.  The  chorda  tympani  nerve 

65.  A  diagram  of  the  course  of  the   vidian 

and   petrosal   NERVES 

66.  a  diagram   of  the  auditory  nerve  and 

its  branches  .... 

67.  Distribution  of  the  cochlear  nerve  . 

68.  General  view  of  the  organ  of  hearing 

69.  A  diagram  to  illustrate  the  mechanism 

of  hearing  .... 

70.  The  ossicles  of  the  tympanum 

71.  The  bony  labyrinth  of  a  new-born  child 

72.  A  diagram  of  the  labyrinth,  vestibule, 

AND   SEMICIRCULAR   CANALS 

73.  A     DIAGRAM     OF     THE     COCHLEA    ON    TRANS- 

VERSE  SECTION  .... 

74.  A     VERTICAL    SECTION     OF     THE     "  ORGAN    OF 

CORTI  "  . 

75.  The  two  pillars  of  the  "  organ  of  Cor- 

Tl" 

76.  Distribution  of  the  cochlear  nerves 

77.  Membrana  tympani,  seen  from  within 

78.  Section  of  the   cochlea  of  the  cat  and 

human  fcetus        .... 

79.  The  glosso-piiaryngeal  nerve 

80.  A     DIAGRAM      OF     THE      GLOSSO-PHARYNGEAL 

NERVE  ..... 

81.  The  papilla  of  the  tongue 

82.  a  circumvallate  papilla    . 

83.  The  fungiform  and   filiform   papilla 

84.  The  taste-buds  .... 

85.  The  cavities  of  the  mouth  and  pharynx 


Flower  (Modified 
Hirschfeld 


Flower 
Hirschfeld 


Ranney 

Corfe   . 

Ranney 
Hirschfeld 

Ranney 

u 
Sappey 


Ranney 
Arnold 
Rudringer 


Ranney 
Waldeyer 
Sappey 
Rudringer 

Sappey 
Ranney 


Engelmann 
Sappey 


xxin 

PAGE 

from)     154 

155 

156 

157 
159 
176 

178 

179 

181 

183 
185 

186 

198 
199 
200 

202 
203 
204 

205 

206 

207 

208 
209 
212. 

214 


222 
223 

224 
224 

226 
228 


XXIV 


LIST  OF  ILLUSTRATIONS. 


FIQ. 

86.  The  muscles  of  the  pharynx 

87.  Anastomoses  of  the  pneumogastric  nerve 

88.  a  diagram  of  the  cervical  portion  of 

the    PNEUMOGASTRIC    NERVE 

89.  a  diagram  of  the  thoracic  and  abdominal 

portions  of  the  pneumogastric  nerve 

90.  Distribution  of  the  pneumogastric  nerve 

91.  Nerves  of  the  larynx,  posterior  view 

92.  Nerves  of  the  larynx,  lateral  view 

93.  Branches  of  the  pneumogastric  nerve 

to  the  heart        .... 

94.  The  spinal  accessory  nerve 

95.  Posterior  view   of  the  muscles  of  the 

larynx      ..... 

96.  Lateral    view    of    the  muscles   of  the 

larynx     ..... 

97.  A  DIAGRAM  of  THE  SPINAL  ACCESSORY  NERVE 

98.  The  glottis,  as  seen  with  the  laryngo- 

scope DURING  THE  EMISSION  OF  HIGH- 
pitched  sounds    .... 

99.  The  spinal  accessory  nerve 

100.  Distribution  of  the  hypo-glossal  nerve 

101.  Anastomotic    loop   formed   by    the  de- 

scending branch  of  the  hypo-glossal 
nerve  and   the   internal  descending 

BRANCH   of   the  CERVICAL  PLEXUS 

102.  a  diagram   of  the  hypo-glossal  nerve 

and  its  branches 

103.  Glosso-labio-laeyngeal  paralysis 

104.  "         "  "  "  .  . 

105.  A   DIAGRAM    OF   THE   MOTOR    POINTS    OF   THE 

FACE,  SHOWING  THE  POSITION  OF  THE 
ELECTRODES  DURING  ELECTRIZATION  OF 
SPECIAL   MUSCLES   AND   NERVES       . 

106.  The    cervical    portion    of    the    spinal 

CORD  ..... 

107.  The  dorsal  portion  of  the  spinal  cord 

108.  Inferior  portion  of  the  spinal  cord  and 

cauda  equina      .... 

109.  Transverse   section  of  the  spinal  cord 

AT   the    origin    of    THE   FIFTH    PAIR    OF 

cervical  nerves 

110.  Transverse  section  of  the  spinal  cord 

of  a  child  six  months  old,  at  the 
middle  of  the  lumbar  enlargement   . 

111.  a  section  of  the  spinal  cord  below  the 

medulla  oblongata 

112.  a  section  of  the  cervical  enlargement 

OF   THE   SPINAL   COED 


Sappey 
Hirachfeld 

Ranney 


Eirgchfeld 
Sappey 


Bernard 
Hlrschfeld 

Sappey 

u 

Ranney 


Le  Bon 
Sajypey 


Hirschfeld 

Ranney 
Hammond 


Rosenthal  (Mod.  from) 
Hirsclifeld 


Stilling 

Gerlach 
Sappey 


PAGE 

230 

237 

23S 

241 
242 
244 
244 

245 

260 

261 

261 
262 


268 
265 

283 


274 

275 

278 
279 


282 

288 

288 

288 


289 

291 
295 
295 


LIST  OF  ILLUSTRATIONS. 


XXV 


FIG. 

113.  a  section  of  the  dorsal  eegion  of  the 

spinal  cord         .... 

114.  a  section  of  the  lumbar   enlargement 

of  the  spinal  cord 

115.  Colored  plate  showing  the  subdivisions 

OF    THE    spinal   CORD 

116.  A  TRANSVERSE    SECTION  OF  THE  SPINAL    CORD 

(Diagrammatic) 

117.  Nerve  cell  from  the  anterior  horn  of 

the  spinal  cord  of  a  calf 

118.  Multipolar  nerve  cell  from  the  ante- 

rior HORN   of   the   spinal   CORD   OF   THE 
OX  ..... 

119.  Transverse    section    of   the   gray   sub- 

stance OF  the  spinal  cord 

120.  Course  of  motor  and  sensory   paths  in 

the  spinal  cord 

121.  Nerve    cells    from    the    floor  of  the 

ehomboidal  sinus  in  man 

122.  a  diagram  to  show  the   decussation  of 

motor   nerve    fibers     IN     THE     MEDULLA 

oblongata  .... 

123.  Atrophic   spinal     paralysis     with    con- 

tracture ..... 

124.  Progressive  muscular   atrophy    of  the 

upper  extremity 

125.  Progressive  muscular  atrophy.    Age  of 

patient,  forty-five  years 

126.  a  diagram  showing  the  relation  of  the 

spinous  processes  of  the  vertebra  to 
the  spinal  nerves  and  spinal  cord 

127.  a  diagram  to  show  the  course  of  the 

motor  and   sensory  paths  in  the  spi- 
NAL  CORD.  .... 

128.  a  diagram   to   show    the    relation    of 

the  spinous   processes  of  the  verte- 
bra to  spinal  nerves    . 

129.  The  cervical  portion  of  the  spinal  cord 

130.  The  dorsal  portion  of  the  spinal  cord 

131.  The  inferior  portion  of  the  spinal  cord 

and  cauda  equina 

132.  Posterior  branch  of  the   second  cervi- 

cal NERVE  .... 

133.  Superficial   branches   of   the   cervical 

PLEXUS       ..... 

134.  The  nerve  supply  of  the  posterior  part 

OF   the   head  .... 

135.  The  nerve  supply  of  the  posterior  por- 

tion OF  the  head  and  neck     . 


Sappey 

296 

a 

296 

Hammond 

297 

Seguin . 

298 

Schultze 

308 

Belters 

305 

Gandry 

306 

Brown-Sequard 

307 

KolUTcer 

308 

Fleclisig  and  Seguin    . 

327 

Hammond 

333 

u 

335 

Friedreich 

336 

Malgaigne  and  Seguin      340 


Brown-Sequard 


349 


Malgaigne  and 
Hirschfeld       . 

Seguin 

350 
356 
356 

u 

356 

Arnold 

363 

Hirschfeld 

365 

Hilton 

366 

Flower 

367 

XXVI 


LIST  OF  ILLUSTRATIONS. 


FIO. 

136.  a  diagram  of  the  bbaohial  plexus  and 

its  bkanohes       .... 

137.  Anteeiob    bbanches    of    the  four    last 

cervical  and  first  doesal  nebves 

138.  collatebal  bbanches   of  the  bbachial 

PLEXUS         ..... 

139.  Bbaohial  pobtion  of  the  musculo-cuta- 

neous,  median,  and  ulnab  nebves 

140.  Cutaneous  nebves  of  the  antebiob  sub- 

face  OF  THE  FOBEABM  AND  HAND 

141.  Cutaneous  nebves  of  the  shouldeb  and 

postebiob  8ubface  of  the  abm    •  . 

142.  Cutaneous  nebves  of  the  postebioe  sub- 

face  OF  THE  FOBEABM  AND  HAND 

143.  BbACHIAL    POBTION   OF   THE    MUSCULO-CUTA- 

neous,  median,  and  ulnab  nebves 

144.  Teeminal    pobtion   of   the   median   and 

ulnab  nebves   .... 

145.  diagbam  of  the  begions  of  the  cutane- 

ous nebve  di8tbibuti0n  on  the  ante- 
eiob subface  of  the  uppee  extbemity 
and  teunk     .... 

146.  The  cutaneous  nebves  of  the  shouldeb 

and  antebiob  subface  of  the  abm 

147.  The  cutaneous  nebves  of  the  antebiob 

subface  of  the  fobeabm  and  hand  . 

148.  BbACHIAL   POBTION    OF   THE    MU8CUL0-CUTA- 

NEOUS,  MEDIAN,  AND   ULNAB  NEBVES 

149.  TeBMINAL    POBTION     OF     THE    MEDIAN     AND 

ulnab  nebves       ..... 

150.  The  oiboumflex  and  subscapulab  nebves 

151.  The  musculo-spiral  nebve  .         ,  . 

152.  The  TEBMINAL  bbanches  of  the  musoulo- 

spibal  nerve 

153.  a  diagbam   of  the   regions   of  cutane- 

ous nebve  distbibution  on  the  poste- 
biob subface  of  the  upper  extbemity 
and  tbunk  .... 

154.  The  motob  points  on  the  outeb  aspect 

of  the  abm  .... 

155.  The  motob  points  on  the  inneb  side  of 

THE   ABM     .  .  .  .  . 

156.  The  motob  points  on  the  extensob  (pos- 

tebioe) ASPECT  of  the  FOBEABM 

157.  The  motob  points  on  the  flexob  (ante- 

biob)  ASPECT  OF  THE  FOBEABM     . 

158.  The  intebcostal  nerves     . 

159.  The  nerves  situated  on  the   postebior 

part  of  the  trunk 


Gray    . 

Uirschfeld 

u 

Sappey 

Hirachfeld 

Sappey 


379 
380 
381 
386 
389 
391 
392 
394 
394 

396 

899 

399 

401 

401 
407 
409 

409 


Flotcer  (Modified  from)    41 1 
Rosenthal    "  "         415 

416 


418 
.       421 

.       423 


Flower 
Hirachfeld 

u 

Sappey 


U  ((  u 


((  u 


LIST  OF  ILLUSTRATIONS. 


XXVll 


FIG. 

160.  A  DIAGRAM  OF   THE   REGIONS    OF    CIJTANE0U8 

NERVE  DISTRIBUTION  IN  THE  ANTERIOR 
SURFACE  OF  THE  UPPER  EXTREMITY  AND 
TRUNK  ..... 

161.  A  DIAGRAM   OF    THE   REGIONS   OF   CUTANEOUS 

NERVE  DISTRIBUTION  ON  THE  POSTERIOR 
SURFACE  OF  THE  UPPER  EXTREMITY  AND 
TRUNK  ..... 

162.  The  lumbar  plexus 

163.  The  cutaneous  nerves  of  the  thigh 

164.  The  muscular  branches  of  the  anterior 

and  internal  portions  of  the  thigh 

165.  a  diagram  of  the  cutaneous  supply  of 

the  anterior  aspect  of  the  lower 
extremity  .... 

166.  Cutaneous  nerves  of  the  anterior  part 

OF   THE   thigh         .  .  . 

167.  Diagram   of    the   cutaneous   supply    of 

the  posterior  aspect  of  the  lower 
extremities  .... 

168.  Muscular  BRANCHES  of  the  anterior  and 

internal   portions   OF   THE   THIGH 

169.  The  small  sciatic  nerve  with  its  branches 

of  distribution  and  termination 

170.  The     great    sciatic     nebve    with    its 

branches  of  distribution  and  ter*- 
mination  ..... 

171.  The  external  popliteal  nerve    . 

172.  The  internal  popliteal  nerve    . 

173.  The  external  saphenous  nerve  and  its 

ACCESSORY,    the    COMMUNICANS    PERONEI 

174.  The  plantar  nerves,  their  course,  anas- 

tomoses, and  distribution 

175.  The  deep  branch  of  the  external  plan- 

tar nerve  .... 

176.  The  motor  points  on  the  posterior  as- 

pect OF  the  thigh 

177.  The  motor  points  on  the  anterior  as- 

pect OF  THE  thigh 

178.  The  motor  points  on  the  inner  aspect 

of  the  leg  .... 

179.  The  motor  points  on  the  outer   aspect 

OF   the   leg  .... 


Flower  (Modified  from)    425 


Hirsclifeld 


429 

435 
442 

445 


Flower  (Modified  from)    446 
Sappey  ,  .      449 

Flower  (Modified  from)     451 

Sappey  .  .453 

"       .  .  .      465 

"  .  .      470 

.      471 
.       473 

"  .  .       475 

"  .  .      476 

.      477 

Eosentlial  (Mod.  from)      480 

482 

484 

486 


u  u 


(;  u 


(I  u 


GENERAL  lE^TRODUCTIOJN'. 

\THE  NERVOUS  SYSTEM  CONSIDERED  AS  A  WHOLE,  AND 
THE  AXIOMS  OF  NERVE  DISTRIBUTION. 


GEITEEAL  INTEODUOTION. 


■■T      GrEiSTTLEMEN :  The  subject  of  the  nerves,  which  has  been 
chosen  as  the  th^me  of  my  winter's  course  of  lectures,  is  one 
which  probably  comprises  more  points  of  practical  interest 
than  any  other  portion  of  anatomy.     I  say  of  practical  inter- 
est, because  there  is  hardly  a  field  of  medicine  or  of  surgery 
where  the  nervous  system  does  not  help  to  explain  many  of 
the  symptoms  which  might  otherwise  tend  to  possibly  mis- 
lead the  practitioner,  and  where  it  does  not  also  afford  invalu- 
able aid  in  the  diagnosis  of  obscure  gLffections  which  might 
remain  unrecognized,  without  a  knowledge  of  the  nerves  and 
of  their  distribution  and  function,  till  the  opportunity  of 
1      relief  to  the  patient  has  passed. 
IB       The  distribution  of  those  small  nerve  filaments  which  sup- 
T      ply  the  skin  of  the  body  with  sensation,  and  thus  allow  of  the 
'      perception  of  external  impressions,  such  as  those  of  heat,  cold, 
pain,  and  touch,  possesses  to-day  an  importance  which  is  not 
confined  to  the  researches  of  the  physiologist,  but  which  the 
advanced  physician  and  surgeon  are  both  keenly  alive  to 
grasp  in  all  its  practical  detail. 

In  every  work  now  published  upon  diseases  of  the  nervous 
system,  you  will  find  plates,  which,  in  less  modem  treatises, 
have  no  analogue ;  which  plates  are  designed  to  show  the 
situation  of  certain  motor  points  on  the  cutaneous  surface  of 
the  different  anatomical  regions  of  the  body,  where  the  elec- 
tric current  can  be  best  applied  to  accomplish  certain  desired 
effects. 


4  GENERAL  INTRODUCTION^, 

The  important  relationship  which  exists  between  the  nerves 
of  the  skin,  the  muscles  underneath  it,  and  the  joints  which 
those  muscles  move,  is  affording  the  enlightened  physician  a 
means  of  tracing  the  seat  of  obscure  affections,  by  the  use  of 
certain  general  rules  governing  the  nerve  supply  of  the  body, 
with  a  degree  of  accuracy  and  ease  which  strikes  those,  not 
familiar  with  the  method,  as  remarkable. 
\j  (  The  investigations  of  Charcot,'  Ferrier,'  Brown- Sequard,' 
Broca,*  Bouillaud,"  Andral,'  and  a  host  of  others,  have 
awakened  the  profession  to  the  fact  that  many  of  the  old 
ideas  of  the  physiology  of  the  brain  and  the  spinal  cord  are 
radically  wrong ;  and  that,  by  symptoms  referable  to  certain 
anatomical  regions,  the  existence  of  disease  tn  certain  corre- 
sponding parts  of  the  brain  or  spinal  cord  may  be  positively 
localized.  To  what  extent  this  new  guide  to  diagnosis,  given 
us  by  means  of  experiments  calculated  to  determine  the  pre- 
cise distribution  of  the  nervons  system,  may  be  developed  in 
the  future,  time  alone  will  show  ;  but  we  have  already  ample 
proof  that  some  positive  information  of  a  practical  charactej? 
has  been  gained,  and  much  advance  has  been  made  in  the 
accurate  knowledge  of  the  anatomy  of  the  nervous  centers. 

When  we  consider  that  every  act  which  distinguishes  the 
animated  being  from  the  corpse  is  dependent  upon  the  influ- 
ence of  the  nerves,  and  that,  without  these  electric  wires,  the 
heart  would  cease  to  throb,  the  lungs  no  longer  perform  their 
function,  the  eye  no  longer  be  capable  of  vision,  the  ear  no 
longer  perceive  sound,  and  that  smell,  taste,  expression,  and 
movement  would  cease  to  exist,  we  can  then  understand  how 
much  of  physiological  interest  must  center  around  this  special 
study,  and  how  necessary  is  the  thorough  understanding  of 
the  distribution  and  function  of  the  individual  nerves,  if  we 

'  "  Localizations  dans  Ics  maladies  c^rebrales." 
2  "■  Functions  of  the  Brain  "  ;  "  Localization  of  Cerebral  Disease." 
2  "  Lectures  on  the  Physiological  Pathology  of  the  Brain." 
4  "  Bull,  de  la  Soc.  Anat.,"  1861. 

'  "  Recherches  experimentales  sur  les  fonctions  du  ccrvcau."     "  Jour,  de  Physiolo- 
gie,"  Paris,  1830.     "Trait6  de  l'Enc6phalite,"  Paris,  1825. 
«  "  Clinique  M6dicalc." 


GENERAL  INTRODUCTION.  5 

ever  hope  to  attain  a  compreliensive  grasp  of  the  general  plan 
of  our  construction. 

During  the  last  session,  I  closed  my  course  of  lectures  with 
a  description  of  the  general  construction  of  nerves  and  the 
anatomy  of  the  human  brain.  It  will  assist  us,  in  our  study  of 
the  distribution  and  practical  utility  of  the  separate  nerves  of 
the  body,  to  hastily  review  the  main  classilications  of  nerves 
and  the  general  plan  upon  which  the  nervous  system  is 
formed. 

The  nervous  system  of  the  human  race  consists  of  the  fol- 
lowing component  parts : 


1st,  Cerebro-spinal 
system. 


(  Brain, 
The  cerebro-spinal  ■<  Medulla  oblongata, 
axis  :  f  Spinal  cord. 


The  motor  nerves. 

The  sensory  nerves. 
2d.  The  sympathetic  nerve, 
8d.  Various  ganglia,  connected  with  special  nerves. 


The  cerebrospinal  axis  includes  those  nerve  centers  in- 
closed within  the  cavities  of  the  cranium,  and  of  the  spinal 


Fig.  1. — Nerve  fibers  from  the  human  subject ;  magnified  350  diameters.     (KOlliker.) 

Four  small  fibers,  of  which  two  are  varicose,  one  medium-sized  fiber  with  borders  of  sin- 
gle contour,  and  four  large  fibers ;  of  the  latter,  two  have  a  double  contour  and  two 
contain  granular  matter. 
3 


GENERAL  INTRODUCTION. 


Fig.  2.— Cervical 


ijiiii>ailutic.    (Sappcy.) 


1,  1,  1,  right  pneumogastric ;  2,  glosso-pharyngcal ;  3,  spinal  accessory;  4,  divided  trunk 
of  the  sublingual ;  6,  6,  5,  chain  of  ganglia  of  the  sympathetic  ;  6,  superior  cervical 
ganglion;  7,  branches  from  this  ganglion  to  the  carotid ;  8.  nerve  of  Jacobson;  9, 
iieo  filaments  from  the  facial,  one  to  the  spheno-palatin^  and  tJie  other  to  the  otic  gan- 
glion ;  10,  motor  oculi  extcrnus  ;  11,  ophthalmic  ganglion,  receiving  a  motor  filament 
from  the  motor  oculi  communis  and  a  sensory  f  lament  from  the  nasal  branch  of  the 
ffth  ;  12,  spheno-palatinc  ganglion  ;  13,  otic  ganglion  ;  14,  lingual  branch  of  the  fifth 


GENERAL  INTRODUCTION.  7 

nerve;  15,  submaxillary  gangVion ;  16,  17,  superior  laryngeal  nerve;  18,  external 
laryngeal  nerve;  19,  20,  recurrent  laryngeal  nerve;  21,  22,  23,  anterior  hranclics  of 
•  the  upper  four  ccri  ical  nerves^  sending  filaments  to  the  superior  cervical  sympathetic 
ganglion;  24,  anterior  branches  of  the  fifth  and  sixth  cervical  nerve  sending  filaments 
to  the  middle  cervical  ganglion  ;  25,  26,  anterior  branches  of  the  seventh  and  eighth 
cervical  and  the  first  doj'sal  nerves,  setiding  filaments  to  the  inferior  cervical  ganglion  ; 
27,  middle  cervical  ganglion  ;  28,  cord  connecting  the  two  ganglia  ;  29,  inferior  cervi- 
cal ganglion  ;  30,  HI,  filaments  connecting  this  with  the  middle  ganglion  ;  32,  superior 
cardiac  nerve  ;  33,  middle  cardiac  nerve  ;  34,  inferior  cardiac  nerve  ;  35,  35,  cardiac 
plexus  ;  36,  ganglion  of  the  cardiac  plexus  ;  37,  nerve  following  the  right  coronary 
artery  ;  38,  38,  intercostal  nerves  with  their  two  filaments  of  communication  with 
the  thoracic  ganglia  ;  39,  40,  41,  great  splanchnic  nerve  ;  42,  lesser  sptlanchnic  nerve  ; 
43,  43,  solar  plexus  ;  44,  left  pneumogastric ;  45,  right  pneumogastric ;  46,  lower  end 
of  the  phrenic  nerve  ;  47,  section  of  the  right  bi'onchus ;  48,  arch  of  the  aorta ;  49, 
right  auricle ;  50,  right  ventricle;  51,  52,  pulmonary  artery ;  53,  right  half  of  the 
stomach ;  54,  section  of  the  diaphragm. 

column,  viz.,  the  brain,  medulla  oblongata,  and  spinal  cord. 
The  second  component  part  of  the  cerebro-spinal  system,  viz., 
the  motor  nerves,  are  efferent  nerves,  which  carry  the  impulses 
of  the  nerve  centers  to  the  muscles.  The  third  component 
part,  the  sensory  nerves,  are  afferent  nerves^  which  carry  only 
sensory  impressions  from  the  periphery  of  the  body  to  the 
nerve  centers,  viz.,  to  the  brain  or  spinal  cord. 

The  sympathetic  nerxe'  comprises  a  continuous  chain  of 
nerve  fibers  and  ganglionic  enlargements,  which  extends  from 
the  head  to  the  coccyx,  on  both  sides  of  the  spinal  column, 
and  which  is  in  constant  communication,  along  its  course, 
with  branches  of  the  cerebro-spinal  system  of  nerves.     It  sup- 
plies branches  to  various  ganglia  of  the  thorax  and  abdomen, 
i  and  helps  to  form  the  plexuses  of  nerves  which  ramify  upon 
I  the  coats  of  all  the  principal  blood-vessels,  and  which  accom- 
!  pany  them  throughout  the  length  of  their  course.     It  is  by 
'  means  of  these  plexuses  upon  the  blood-vessels  that  the  sym- 
pathetic nerve  is  enabled  to  control  the  involuntary  muscular 
I  fibers  within  the  coats  of  the  blood-vessels,  and  thus  to  regii- 
i  late  the  vascular  supply  of  the  various  tissues  and  organs  of 
the  body  ;  and  the  nerve  fibers  of  the  sympathetic  are  there- 
fore often  called  the  ''nerves  of  organic  life,"  since  they  regu- 
late the  life  of  tissues  by  controlling  their  blood  supply,  while 
the  cerebro-spinal  nerves    are    contradistinguished   as    the 
"nerves  of  animal  life,"  since  they  control  those  acts  which 
are  essential  to  the  life  of  the  individual,  such  as  muscular 

1  See  Fig.  2  and  Fig.  3. 


GENERAL  INTRODUCTION. 


Fig.  3. — Lumbar  and  sacral  portions  of  the  sympathetic.     (Sappey.) 

1,  section  of  the  diaphragm  ;  2,  lower  end  of  the  oesophagus ;  o,  left  half  of  the  stomach ; 
4,  small  intestine ;  6,  sigmoid  flexure  of  the  colon ;  6,  rectum ;  7,  bladder ;  8,  pros- 
tate ;  9,  lower  end  of  the  left  pneumogastvic  ;  10,  lower  end  of  the  right  pncumogas- 
trie;  11,  solar  plexus;  12,  lover  end  of  the  great  splanchnic  nn-ve  ;  13,  lower  aid  nf 
the  lesser  splanchnic  nerve  ;  14,  14,  last  tico  thoracic  ganglia  ;  15,  .15,  the  four  lumbar 
ganglia;  16,  16,  17,  17,  branches  from  the  lumbar  ganglia;  18,  superior  mesenteric 
plexus;  19,  21,  22,  23,  aortic  lumhar plexus ;  20,  infenor  mesenteric  plexus;  24,  24, 
saa^al  portion  of  the  si/mpaihetic  ;  25,  25,  26,  26,  27,  27,  hypogastric  plexus  ;  28,  29, 
30,  tenth,  eleventh,  and  twelfth  dorsal  nerves  ;  31,  32,  33,  34,  35,  36,  37,  38,  39,  lum- 
bar  and  sacral  nerves. 


GENERAL  INTRODUCTION. 


9 


movement,  respiration,  etc.  The  frequent  communication  be- 
tween tlie  sympathetic  nerves  and  those  of  the  cerebro-spinal 
system  renders  the  actions  of  the  two  systems  in  perfect  ac- 
cord, and  thus  supports  the  universal  law  of  Jiarmony  which 
is  so  beautifully  illustrated  in  all  the  works  of  ]S"ature. 

The  cerebro-spinal  nerves  comprise  those  which  escape 
from  the  foramina  of  the  cranium,  called  the  cranial  nerves^ 
and  those  which  are  given  off  from  the  spinal  cord,  which 
escape  from  the  spinal  canal  by  means  of  foramina  between 
the  laminse  of  the  vertebrae,  called  the  ''inter- vertebral  fora- 
mina." These  latter  nerves  are  called  spinal  nerves^  in  con- 
tradistinction to  the  cranial  nerves. 

All  of  the  spinal  nerves  arise  by  tico  roots^  thus  indicating 
that  they  are  provided  with  both  motor  and  sensory  fila- 
ments, the  former  of  which  constitute  the  an- 
terior and  the  latter  the  posterior  root ;  while 
the  cranial  nerves  are,  in  some  instances, 
similarly  constructed,  as  to  having  two  dis- 
tinct roots,  while  others  have  only  one.  The 
reason  of  this  anatomical  variation  is  ex- 
plained by  the  fact  that  some  of  the  cranial 
nerves  are  destitute  of  motor  fibers,  some  of 
sensory  fibers,  while  others  are  endowed  with 
a  special  function,  such  as  sight,  smell,  hear- 
ing, and  taste. 

In  the  course  of  lectures  which  I  propose 
to  deliver  before  you  this  winter,  it  is  my  in- 
tention not  only  to  give  the  anatomical  ori- 
gin, course,  and  distribution  of  the  various 
nerves,  but  also  such  points  of  practical  value 
as  may  be  suggested  in  connection  with  each, 
which  will  aid  in  remembering  the  peculi- 
arities which  each  presents,  and  possibly  to 
guide  you  in  your  practice  at  the  bedside  of 
the  sick. 

The  study  of  the  practical  bearing  of  the 
distribution  of  the  nerves  is  to-day  assuming 


Fig.  4. — Fibers  of 
Remak ;  magni- 
fied 300  diame- 
ters.    (Robin.) 

With  the  gelatinous 
fibers  are  seen 
two  of  the  ordina- 
ry, dark-bordered 
nerve  fibers. 


10 


GENERAL  INTRODUCTION. 


an  importance  in  diagnosis  wliicli  can  not  be  over-estimated  ; 
while  the  physiological  phenomena  produced  by  them  have 
a  direct  influence  upon  the  proper  performance  of  all  those 
functions  of  the  body  which  may  be  considered  as  vital  to  it. 
It  is  claimed  by  John  Hilton '  that,  if  we  trace  the  dis- 
tribution of  the  motor  nerve  fllaments  from  any  special  nerve 
trunk  to  the  muscles,  we  shall  find  that  only  those  muscles 
are  supplied  by  each  of  the  individual  nerves  which  are  re- 
quired to  render  the  performance  of  the  functions^  for  which 
that  nerve  was  designed,  complete  ;  and  that,  if  muscles  were 
classified  on  a  basis  of  their  nerve  supply,  instead  of  in 
groups  of  mere  relationship  as  to  locality,  a  self-evident  phy- 
siological relation  would  be  shown  which  would  tend  greatly 


Fia.  5. — Mode  of  termination  of  the  motor  nerves.     (Rouget.) 

A,  primitive  fasciculus  of  the  thyro-hyoid  muscle  of  the  human  subject,  and  its  nerve 

tube:  1,  1,  primitive  muscular  fasciculus;  2,  nerve  tube;  3,  medullary  substance  of 
the  tube,  which  is  seen  extending  to  tlie  terminal  plate,  where  it  disappears ;  4,  ter- 
minal plate  situated  beneath  the  sarcolemma,  that  is  to  say,  between  it  and  the  ele- 
mentary fibrillae ;  5,  5,  sarcolemma. 

B.  primitive  fasciculus  of  the  intercostal  muscle  of  the  lizard,  in  which  a  nerve  tube  ter- 

minates: 1,  1,  sheath  of  the  nerve  tube;  2,  nucleus  of  the  sheath;  3,  3,  sarcolemma 
becoming  continuous  with  the  sheath ;  4,  medullary  substance  of  the  nerve  tube  ceas- 
ing abruptly  at  the  site  of  the  terminal  plate ;  5,  5,  terminal  plate ;  6,  6,  nuclei  of 
the  plate ;  7,  7,  granular  substance  which  forms  the  principal  clement  of  the  terminal 
plate,  and  which  is  continuous  with  the  axis  cylinder;  8,  8,  undulations  of  the  sarco- 
lemma reproducing  those  of  the  fibrillie ;  9,  9,  nuclei  of  the  sarcolemma. 


to  simplify  a  knowledge  of  the  muscular  system  in  its  prac- 
tical bearings,  and  to  prove  a  design  on  the  part  of  the 
Creator. 

^  "  Rest  and  Pain,"  Loudon.     (Now  York,  1879.) 


GENERAL  INTRODUCTION.  11 

Thus,  lie  says,  we  frequently  find  muscles  close  together 
and  still  supplied  by  separate  nerves,  one  of  which  has  possi- 
bly to  go  a  long  way  out  of  a  direct  course  to  reach  it,  which 
is  contrary  to  the  usual  method  of  JS'ature,  who  always  em- 
ploys the  simplest  means  to  accomplish  her  designs ;  but,  if 
we  examine  the  action  of  these  two  muscles,  we  shall  find 
that  each  one  acts  in  unison  with  the  other  muscles  sup- 
plied by  the  same  nerve,  and  that  to  produce  this  perfect 
accord  Nature  takes  what,  to  a  hasty  glance,  would  seem  to 
be  a  needless  step. 

He  also  lays  down  certain  axioms,  pertaining  to  the  distri- 
bution of  nerves  and  the  diagnostic  value  of  pain,  which  will 
be  often  repeated  in  these  lectures,  and  can  not  but  be  most 
profitable  to  those  who  use  them  as  a  guide.  They  are  as 
follows : 

"Superficial  pains  on  both  sides  of  the  body,  which  are 
symmetrical,  imply  an  origin  or  cause,  the  seat  of  which  is 
central  or  bilateral ;  while  unilateral  pain  implies  a  seat  of 
origin  which  is  one-sided,  and,  as  a  rule,  exists  on  the  same 
side  of  the  body  as  thepain^ 

The  bearings  of  this  first  axiom  will  be  rendered  far  more 
apparent  when  the  regions  of  the  neck  and  trunk  are  con- 
sidered, since  the  symptom  of  local  pain  is  of  the  greatest 
value  in  connection  with  diseases  affecting  the  bones  of  the 
spinal  column  and  the  spinal  cord  which  they  invest ;  but  the 
same  rule  may  be  applied  to  any  of  the  cranial  nerves,  with  a 
degree  of  certainty  which  seldom  admits  of  error. 

Thus  Hilton  reports  a  case  where  a  fracture  of  the  base  of 
the  skull,  involving  the  orbit,  produced  amaurosis  and  tension 
of  that  region,  with  extreme  local  pain.  A  grooved  probe, 
passed  along  the  roof  of  the  orbit,  revealed  pus,  as  was  sus- 
pected to  exist,  which  was  evacuated  by  the  separation  of  the 
blades  of  an  ordinary  dressing  forceps. 

As  further  examples  of  this  axiom,  a  toothache  may  thus 
accompany  an  inflamed  condition  of  tlie  temporo-maxillary 
articulation,  or  it  may  create  it.  Again,  opium  introduced 
into  the  auditory  canal  will  often  instantaneously  relieve 


12  GENERAL  INTRODUCTION, 

toothache  and  stiffness  of  the  jaws,  by  having  a  narcotic  effect 
upon  the  peripheral  filaments  of  the  same  nerves,  whose  main 
trunks  are  distributed  to  the  other  regions  mentioned  as  re- 
lieved. 

Severe  earache  may  result  directly  from  the  nervous  irri- 
tation of  a  diseased  tooth,  since  the'filaments  of  the  fifth  nerve 
are  distributed  to  both  the  ear  and  the  teeth,  and  thus  pain 
may  be  felt  at  a  point  apparently  disconnected  from  the  seat 
of  irritation. 

Earache  is  frequently  the  result  of  malignant  ulceration 
of  the  tongue,  since  both  regions  receive  a  portion  of  their 
nervous  supply  from  the  fifth  cranial  nerve. 

The  second  axiom  is  as  follows : 

''  TJie  same  trunks  of  nerves^  whose  branches  supply  the 
groups  of  muscles  moving  a  joint  furnish  also  a  distribution 
of  nerves  to  the  skin  over  the  insertions  of  the  same  muscles  ; 
and  the  interior  of  the  joint  moved  by  these  muscles  receives 
a  nerve  supply  from  the  same  source.^^ 

By  this  axiom,  a  physiological  harmony  is  created  between 
these  various  cooperating  structures.  Thus  any  joint,  when 
inflamed,  may,  by  a  reflex  act  through  motor  branches  de- 
rived from  the  same  trunk  by  which  it  is  itself  supplied,  con- 
trol the  muscles  which  move  it,  and  thus  insure  the  rest  and 
quiet  necessary  to  its  own  repair. 

Spots  of  local  tenderness  in  the  cutaneous  surface  may, 
for  this  reason,  likewise  be  often  considered  as  a  guide  to  a 
source  of  irritation  of  some  of  the  structures  supplied  by  the 
same  nerve,  viz.,  the  muscles  underneath  it,  or  the  joints 
which  are  moved  by  them ;  and  thus  even  remote  affections 
can  be  accurately  determined,  which,  were  this  axiom  not 
used  as  a  guide,  might  escape  recognition  till  an  advanced 
stage  of  the  disease  had  been  reached. 

It  is  well,  however,  to  quote  one  other  axiom,  laid  down 
by  the  same  author,  before  leaving  the  subject  of  the  diag- 
nostic value  of  the  cutaneous  nerves  as  indicators  of  existing 
disease  of  other  organs,  viz.  : 

"  Every  fascia  of  the  body  has  a  muscle  or  muscles  at- 


GENERAL  INTRODUCTION.  13 

tacJied  to  it^  and  eceYy  fascia  must  he  considered  as  one  of 
the  points  of  insertion  of  the  muscles  connected  to  it,  in  fol- 
lowing the  previous  axiom  as  to  the  cutaneous  distribution  of 
nerves." 

This  guide  is  especially  important  in  case  the  rule  should 
be  applied  to  the  extremities  (arms  and  legs)  where  these  fasciae 
extend  over  large  surfaces,  more  or  less  remote  from,  and  ap- 
parently unconnected  with,  the  muscles  attached  to  them  ;  but 
it  is  mentioned  in  this  connection,  for  the  special  object  of 
calling  your  attention  to  those  general  rules  which  govern 
the  distribution  of  the  nerves  in  their  entirety,  before  proceed- 
ing to  apply  them  in  all  their  individual  bearings. 

Without  this  nervous  association  between  the  muscular 
structures  and  those  composing  the  joints,  there  could  be  no 
intimation  given  by  the  internal  parts  of  their  exhaustion  or 
fatigue.  Again,  through  the  medium  of  this  same  association 
between  the  skin  and  the  muscles,  great  security  is  given  to 
the  joints,  by  the  muscles  being  made  aware  of  the  point  of 
contact  of  any  extraneous  force  or  violence.  Their  involun- 
tary contraction  instinctively  makes  the  tissues  surrounding 
the  joints  tense  and  rigid,  and  this  brings  about  an  improved 
defense  for  the  sub-adjacent  joint  structures. 

From  the  conclusion  of  his  great  work,  in  which  Hilton ' 
endeavors  to  prove  that  mechanical  rest  may  be  used  as  a 
cure  for  most  of  the  surgical  disorders,  the  following  sen- 
tences are  quoted,  since  they  can  not  be  too  often  repeated  ; 

''I  have  endeavored  to  impress  upon  you  the  fact  that 
every  pain  has  its  distinct  and  pregnant  signification  if  we 
will  hut  carefully  search  for  it. 

''From  the  pain  which  follows  the  intrusion  of  a  particle 
of  dust  on  to  the  conjunctiva,  and  the  closure  of  the  eyelid 
for  the  security  of  rest,  up  to  the  most  formidable  diseases 
which  we  have  to  treat,  pain  the  monitor,  and  rest  the  cure, 
are  starting  points  for  contemplation,  which  should  ever  be 
present  to  the  mind  of  the  surgeon." 

Let  us  now  pass  to  the  special  consideration  of  the  brain 

^  Op.  cit. 


14:  GENERAL  INTRODUCTION: 

and  each  of  the  twelve  nerves  of  the  cranium,  and  note  the 
more  important  facts  presented  by  each,  which  may  tend  to 
elucidate  its  function,  or  to  explain  many  direct  and  reflex 
phenomena  which  are  often  of  great  value  in  the  diagnosis  of 
obscure  aifections. 

Later  in  the  course,  we  will  consider  the  anatomy  of  the 
spinal  cord  and  the  nerves  which  arise  from  it,  noting,  in  each 
instance,  such  points  as  tend  to  elucidate  the  function  of  the 
part  under  consideration,  and  also  such  clinical  facts  as  can 
be  constantly  applied  in  your  daily  association  with  the  sick, 
when  difficult  questions  of  diagnosis  arise,  or  when  valuable 
suggestions,  as  to  the  methods  of  treatment  employed,  seem 
to  be  the  direct  outgrowth  of  your  anatomical  study. 

Some  three  years  since,  my  friend  Professor  E.  C.  Seguin 
addressed  a  class,  in  beginning  a  course'  upon  a  somewhat 
similar  subject,  with  words  of  counsel  and  earnest  pleading 
for  higher  professional  attainments,  which  are  well  worthy  of 
repetition.  I  therefore  quote  them  to  you  in  the  same  spirit, 
trusting  that  they  will  kindle  in  you  a  renewed  vigor  and  en- 
thusiasm in  this  special  department  of  science : 

"  In  practice,  when  we  have  completed  the  examination  of 
a  patient,  several  questions  are  put  to  us  by  the  patient,  by 
his  friends,  or  by  ourselves.  These  are,  in  chronological  order : 
Is  there  disease  i  Where  is  the  disease  ?  What  is  the  disease  ? 
What  are  we  to  do  for  the  cure  of  the  disease  or  for  the  relief 
of  the  patient  ?    Will  the  patient  die  or  recover  ? 

"Of  these  questions,  the  one  which  our  client  and  the 
world  at  large  consider  the  most  important  is  the  fourth— that 
relating  to  treatment  and  cure.  This  preference  is  natural, 
but  highly  unscientific  ;  it  is  a  manifestation  of  that  untrained 
mental  action  which  demands  results  and  scorns  methods, 
which  welcomes  empirical  achievements  (provided  they  be 
agreeable),  and  which  conduces  to  the  perpetuation  of  quack- 
ery of  all  kinds.  But,  to  the  physician  who  is  not  a  mere  pre- 
scription writer,  who  aims  at  infusing  as  much  science  into 

*  Delivered  before  the  students  of  the  College  of  Physicians  and  Surgeons  of  New 
York  City,  1878. 


GENERAL  INTRODUCTION,  15 

his  practice  as  possible,  and  who  believes  that  he  is  not  in  the 
world  for  the  purpose  of  gratifying  his  patients  at  so  much 
per  visit,  but  that  he  owes  himself  a  debt  of  training  and  self- 
culture,  and  who  has  a  sincere  regard  for  science — to  such  a 
physician  the  first  three  questions  assume  a  Justly  great  im- 
portance. Pray  observe  that  I  do  not  say  paramount  impor- 
tance, but  great  importance.  And  the  superiority  of  the  hu- 
manitarian over  the  scientific  duty  becomes  less  glaring  if  we 
bear  in  mind  the  truth — and  I  firmly  believe  it  to  be  such — 
that  success  in  treatment  now  depends,  and  in  the  future  will 
still  more  closely  depend,  upon  the  scientific  study  of  the  hu- 
man subject  in  health  and  disease.  In  other  words,  I  would 
impress  you  with  my  own  conviction  that  the  best-trained  and 
most  scientific  physician,  if  he  be  not  a  closet  student  and  the- 
orizer,  is  the  best  practitioner. 

"We  occasionally  hear  of  an  over-fine  diagnosis,  of  ex- 
treme caution  in  the  treatment  of  disease,  and  of  the  sweeping 
application  of  physiological  laws  to  practice  by  men  who  are 
said  to  be  '  too  scientific '  ;  but  who  can  number  the  errors,  nay, 
the  sacrifices  of  life,  which  must  be  laid  at  the  door  of  the 
falsely  so-called  'practical  men,'  who  despise  learning  and 
scientific  methods?  Those  of  us  who  see  something  of  the 
rarer  and  more  formidable  kinds  of  disease  fully  realize  that 
in  medicine,  as  probably  in  other  applicable  sciences,  igno- 
rance leads  to  rashness  and  crudity  in  practice,  while  ripe 
knowledge  conduces  to  success,  or,  at  any  rate,  to  caution  in 
prognosis  and  expectancy  in  treatment. 

"Of  the  three  diagnostic  questions  —  Is  there  disease? 
Where  is  the  disease  ?  What  is  the  disease  % — the  second  is 
the  one  which  forms  the  key-note  of  these  lectures.  Where 
is  the  lesion  producing  the  disordered  actions  or  symptoms  ? 
The  method  to  be  followed  in  arriving  at  the  solution  of  this 
question  varies  somewhat  in  different  departments  of  medi- 
cine. Some  lesions  can  be  seen  by  the  trained  unaided  eye, 
or  felt  by  the  skilled  hand ;  the  seat  of  others  can  be  deter- 
mined by  auscultation  and  percussion,  by  the  aid  of  instru- 
ments, such  as  the  ophthalmoscope,  laryngoscope,  speculum. 


16  GENERAL  INTRODUGTIOK 

etc.  But,  in  the  study  of  the  nervous  system,  greater  difficul- 
ties are  met  with  ;  we  are,  to  a  great  extent,  deprived  of  these 
physical  aids ;  we  can  not  appreciate  the  condition  of  the 
brain  and  spinal  cord  directly  by  our  special  senses,  but  only 
by  a  proper  interpretation  of  the  way  in  which  the  functions 
of  these  parts  are  performed.  In  other  words,  the  diagnosis 
must  be  made  chiefly  by  reasoning." 

To  the  words  above  quoted,  I  can  add  nothing,  save  an 
earnest  endeavor  to  so  place  the  subject  matter  before  you  as 
to  render  it  within  the  grasp  of  your  full  comprehension,  pro- 
vided you,  in  turn,  earnestly  seek  to  master  it. 


THE  BRAIN. 

ITS  ANATOMY,  FUNCTIONS,  AND  CLINICAL  ASPECTS. 


THE    BEAIISr 


It  is  with  a  sense  of  the  difficulty  of  this  task  that  I  en- 
deavor to  select,  from  an  enormous  amount  of  experimental 
research  regarding  the  anatomy  of  the  encephalon,  or  brain, 
such  points  as  seem  to  be  of  special  interest,  or  which  may 
be  made  a  basis  of  reasoning  when  circumstances  arise  that 
demand  analytical  inquiry  into  the  probable  cause  of  any  dis- 
eased condition  which  may  exist.  The  anatomy  of  the  brain 
is  so  complex  that  it  can  be  treated  of  to  advantage  only  by 
a  minute  a^d  fully  illustrated  description,  such  as  can  be 
found  either  in  exhaustive  anatomical  works  or  in  treatises 
upon  the  special  descriptive  anatomy  of  the  nervous  system. 
In  addition  to  this  cause  of  impediment,  w^e  are,  as  yet,  igno- 
rant of  the  exact  structure  of  many  of  its  parts,  and  also  of 
the  arrangement  and  physiology  of  other  portions. 

The  brain  consists  of  a  number  of  ganglia  which  are  con- 
nected with  each  other,  and  also,  by  means  of  the  different 
columns  of  the  spinal  cord,  with  the  motor  and  sensory  nerves 
of  the  head,  the  trunk,  and  the  upper  and  lower  extremities. 

tiie  functions  of  some  of  these  separate  ganglia  are  more  or 
ss  completely  understood ;  but  there  still  exist  masses  of 
gray  substance  scattered  throughout  the  brain,  the  special 
physiological  bearings  of  which  are  as  yet  obscure  or  com- 
pletely unknown.  The  gray  matter  of  the  hemispheres  of  the 
cerebrum  has  been,  and  still  is,  a  source  of  perplexity  to  the 
experimental  physiologist ;  and  while  the  fact  seems  proven 
that  distinct  portions  of  this  large  expanse  of  gray  matter 


20 


THE  BRAm. 


have  each  some  special  function,  it  is  still  impossible,  as  yet, 
to  say  positively  what  the  properties  of  each  locality  are. 


Fig.  6, — A  diagram  of  the  brain  in  profile.     (Modified  from  Quain.) 

This  cerebrum  is  represented  in  this  diagram  as  separated  from  the  cerebellum  more 
than  it  naturally  should  be,  in  order  to  show  certain  important  parts.  A,  the  cere- 
brum ;  B,  the  cerebellum  ;  C,  the  pons  Varolii ;  D,  the  medulla  oblongata  ;  E,  the 
c?*M.s  i-erebri  ;  F,  the  olivary  body  ;  G,  the  tubercula  quadrigemina  ;  S,  the  fismire  of 
Sylvius  ;  R,  the  fissure  of  Rolando  ;  a^  peduncles  of  cerebrum  ;  b,  superior  peduncles 
of  the  cerebellum. ;  c,  middle  peduncle  of  the  cerebellum  ;  d,  inferior  peduncles  of  the 
cerebellum  ;  b,  E,  a,  form  the  isthmus  cncephali. 

If  we  confine  ourselves,  then,  strictly  to  the  limits  of  posi- 
tive information,  we  can  recognize  only  the  following  parts  as 
distinct  ganglia : '  1.  The  gray  matter  of  the  cerebral  hemi- 
spheres ;  2.  The  gray  matter  of  the  cerebellum  ;  3.  The  olfac- 
tory ganglia ;  4.  The  gray  matter  of  the  corpora  striata ;  5. 
The  gray  matter  of  the  optic  thalami ;  6.  The  tubercula 
quadrigemina ;  7.  The  gray  matter  of  the  pons  Varolii,  or  the 
tuber  annulare  ;  8.  The  ganglion  of  the  medulla  oblongata." 

There  are  other  parts  of  the  encephalon  which  have  been 
the  field  of  speculation  and  investigation,  but  the  positive 
knowledge  gained  has  been  of  a  purely  anatomical  character,' 
and  little  is  yet  known  of  their  physiological  import.     As  will 

'  See  Figs.  6,  7,  and  8  of  this  volume. 

'  Darling  and  Ranney,  "  Essentials  of  Anatomy."  G.  P.  Putnam's  Sons :  New  York, 
1880. 

'  See  articles  by  Flechsig,  Luschka,  Charcot,  Lockhart  Clarke,  Daltou,  Spitzka,  and 
many  others. 


GENERAL    CONSTRUCTION. 


21 


be  mentioned  in  the  description  of  the  deep  fibers  of  origin  "^ 
of  some  of  the  cranial  nerves,  the  anatomical  arrangement 
may  often  suggest  hypotheses  which  are  attractive,  and  which 
tend  to  explain  the  object  which  Nature  had  in  view  in  so 


Fig.  T. —  Vertical  section  of  the  encephalon.     (Hirschfeld.) 

1,  medulla  oblongata  ;  2,  tuher  annulare  ;  3,  cerebral  peduncle  ;  4,  cerebellum  ;  5,  aque- 
duct of  Sylvius;  6,  valve  of  Vieussens  ;  7,  tubercula  quadrigemina  ;  8,  pineal  gland  ; 
9,  inferior  peduncle  ;  10,  superior  peduncle  ;  11,  middle  portion  of  the  great  cerebral 
fissure;  VI,  optic  thalamus  ;  13,  13,  gray  commissure  ;  14,  choroid  plexus ;  15,  infun- 
dibulum  ;  \%, pituitary  body  ;  17,  tuber  cinereum;  18,  bulb  of  the  fornix;  19,  ante- 
rior perforated  space  ;  20,  root  of  the  motor  oculi  communis;  21,  optic  nerve;  22, 
anterior  commissure  of  the  cerebrum  ;  23,  foramen  of  Monro ;  24,  section  of  the  for- 
nix ;  25,  septum  lucidum  ;  26,  27,  28,  corpus  callosum  ;  29,  30,  31,  32,  33,  34,  convo- 
lutions and  sulci  of  the  cerebrum.  The  olfactoi'y  ganglia  and  corpora  striata  are  not 
shown  in  this  section. 


constructing  the  part ;  yet  many  of  these  theories  depend 
upon  well- observed  clinical  facts  rather  than  upon  experi- 
mental research. 

The  limited  space  of  time  which  we  can  devote  to  this 
course  of  lectures  will  preclude  the  insertion  of  much  that  is 
purely  anatomical,  and  thus  a  full  comprehension  of  many 
of  the  points  mentioned  may  be  rendered  difficult,  unless  you 
occasionally  consult  some  of  the  text-books  upon  that  sub- 
ject, in  case  any  of  the  terms  used  are  unfamiliar.  Many 
statements  may  also  appear  somewhat  dogmatic,  since  it  will 

^  See  Lectures  on  "  Optic,  Third,  and  Fifth  Nerves,"  in  particular. 
4 


22 


THE  BRAIN. 


not  be  possible  to  enter  into  all  the  methods  of  investigation 
from  which  some  of  the  conclusions  have  been  drawn,  or  to 
quote  authorities  in  support  of  every  proposition  where  there 
chances  to  be  a  conflict  of  opinion. 

Weight  of  the  Brain  and  of  its  Component  Parts. — 
That  the  shape  of  the  cranium  may  be  employed  to  estimate 
the  relative  size  of  the  different  parts  of  the  encephalon,  and 
that  the  circumference  of  the  head  and  the  height  of  the  skull 
above  the  orifice  of  the  ear  may  also  relatively  indicate  the 
measurements  of  the  cerebrum  and  its  basal  ganglia  (which 


Fio.  8. — A  diagram  of  brain  in  transverse  vertical  section.     (After  Dalton.) 

1 ,  cms  cerebri  ;  2,  internal  capsule  ;  3,  optic  thalamus  ;  4,  corpus  striatum  ;  C  C,  corpus 
callosum  ;  L  N,  lenticular  nucleus  ;  S,  fissure  of  Sylvius  ;  Fo,  gyrus  fornicatus  ;  F', 
first  frontal  convolution;  F",  second  frontal  convolution;  F'",  third  frontal  convo- 
lution ;  T',  first  temporal  convolution ;  T",  second  temporal  convolution ;  T'",  third 
temporal  convolution  ;  H,  gyrus  hippocampi. 


are  inclosed  within  it),  have  already  been  pointed  out  in  pre- 
vious lectures  which  I  have  delivered  before  you.  The  varia- 
tions in  the  skulls  of  the  different  nations  indicate  an  amount 
of  brain  which  is  in  the  direct  ratio  to  the  facial  angle  of 
Camper. '  The  average  weight  of  the  brain  of  a  healthy  adult 
of  the  Caucasian  race  has  been  given,  by  most  of  the  promi- 

'  See  article  by  the  author  on  the  "  Osteology  of  the  Head,"  '*  Medical  Record,"  Octo- 
ber 16,  1880. 


WEIGHT   OF  COMPONENT  PARTS. 


23 


nent  investigators  upon  this  subject,  as  about  fifty  ounces  in 
the  male,  and  some  six  ounces  less  in  the  female.'  In  the 
new-born  infant,  the  weight  of  the  brain,  in  the  two  sexes,  is 
more  nearly  alike,  being  in  the  region  of  eleven  ounces  for 


Fig.  9. — Inferior  aspect  of  the  encephalon.     (After  Hirschfeld.) 

1,1,  anterior  lobe  of  the  cerebrum  ;  2,  sphenoidal  portion  of  the  posterior  lobe  ;  3,  3,  oc- 
cipital portion  of  the  same  lobe ;  4,  anterior  extremity  of  the  median  fissure ;  5,  pos- 
terior extremity  of  the  same  ;  6,  6,  fissure  of  Sylvius  ;  7,  anterior  perforated  space  ; 
8,  tuber  cinereum  and  pituitary  body  ;  9,  corpora  albicantia  ;  10,  interpeduncular 
space  (posterior  perforated  space);  11,  crura  cerebri;  12,  pons  Varolii;  13,  me- 
dulla oblongata;  14,  anterior  pyramids;  15,  olivary  body ;  16,  restiforra  body  (only 
partially  visible);  17,  17,  hemispheres  of  the  cerebellum;  18,  fissure  separating 
these  hemispheres ;  19,  19,  first  and  second  convolutions  of  the  inferior  aspect  of 
the  frontal  lobe  with  the  intervening  sulcus ;  20,  external  convolutions  of  the  frontal 
lobe;  21,  optic  tract;  22,  olfactory  nerve ;  22',  section  of  olfactory  nerve,  showing 
Its  triangular  prismatic  shape  :  the  trunk  has  been  raised  to  show  the  sulcus  in  which 
it  is  lodged  ;  23,  ganglion  of  the  olfactory  nerve  ;  24,  optic  chiasm  ;  25,  motor  oculi ; 
26,  pathcticus  ;  27,  trigeminus ;  28,  abducens  ;  29,  facial ;  30,  auditory  nerve  and 
nerve  of  Wrisberg ;  31,  glosso-pharyngeal ;  32,  pneumogastric ;  3,  3,  spinal  accessory ; 
34,  hypo-glossal. 

the  male  child  and  ten  ounces  for  the  female.  The  rapidity 
of  growth  of  the  brain  is  not  uniform  throughout  the  differ- 
ent periods  of  life,  since  it  grows  rapidly  until  the  age  of 

'  See  researches  of  Reid,  Tiedmann,  Sims,  and  Quain. 


24  THE  BRAIN. 

seven  years,  then  less  rapidly  until  the  age  of  forty  is 
reached,  when  it  attains  its  full  development,  and  after  that 
age  it  decreases  in  weight  about  one  ounce  for  every  period 
of  ten  years. 

The  comparative  weights  of  the  component  parts  of  the 
encephalon  are,  in  approximate  figures,  about  one  fiftieth  of 
the  entire  weight  for  the  pons  Varolii  and  the  medulla  oblon- 
gata, taken  together ;  one  tenth  of  the  entire  weight  for  the 
cerebellum  ;  and  the  balance  of  the  total  weight  for  the  cere- 
brum and  the  basal  ganglia  inclosed  within  its  substance. 
These  proportions  also  show  a  slight  variation  in  the  two  sexes, 
but  not  to  so  marked  an  extent  as  to  render  this  statement  far 
from  a  correct  one. 

It  may  be  stated,  as  a  rule,  that  the  relative  proportion  of 
the  cerebrum  to  that  of  the  cerebellum  is  greater  in  the  intel- 
lectual races  ;  and  that  the  cerebrum  is  developed  in  individ- 
uals in  proportion  to  their  intellectual  power,  although  the 
absolute  size  may  not  be  taken  as  a  guide  to  the  quality  of  the 
mind,  since  it  is  undoubtedly  true  that  the  brain  can  be  im- 
proved, in  quality,  by  exercise,  as  well  as  the  muscular  tissue. 
That  there  are  important  individual  differences  in  the  quality 
of  the  generating  nervous  matter  is  evidenced  by  the  fact  that 
some  small  brains  actually  accomplish  more  and  better  work 
than  larger  ones,  and  that  many  women  often  show  a  higher 
degree  of  mental  acumen  than  men,  in  spite  of  the  fact  that 
they  have  brains  which  are  lighter  in  avoirdupois. 

From  the  most  carefully  prepared  table  of  the  weight  of 
brain  substance  possessed  by  men  of  renown  as  intellectual 
giants,  as  well  as  those  which  revealed  an  unusual  develop- 
ment of  brain  after  death,  contained  in  the  work  of  a  promi- 
nent author,*  the  following  interesting  facts  are  revealed  : 

The  heaviest  brains "  on  record  (where  the  statements  are 
to  be  relied  upon)  were  possessed  by  a  congenital  imbecile  and 
an  ignorant  bricklayer,  both  of  whom  outweighed  Cuvier  and 

1  A.  Flint,  Jr.,  "  Text-Book  of  Physiology."     D.  Appleton  &  Co.,  New  York. 

'  Con{^enital  imbecile,  aged  thirty,  70^  ounces  of  brain  substance;  bricklayer,  67 
ounces;  Cuvier,  64 J  ounces;  Abercrombie,  63  ounces ;  Webster,  53^  ounces;  Agassiz, 
53^  ounces. 


THE   CEREBRUM. 


25 


Abercrombie  ;  while  a  boy  of  thirteen  years  of  age  had  five 
ounces  more  brain  than  Webster  and  Agassiz.  Such  a  table 
shows  the  utter  absurdity  of  attempting  to  apply  to  individu- 
als the  rule  that  the  greatest  brain  power  is  possessed  by  the 
one  possessing  the  greatest  amount  of  brain  substance. 


Fig.  10. — Convolutio7is  on  the  internal  aspect  of  the  hemisphei-es.     (After  Sappey.) 

1,  frontal  lobe ;  2,  sphenoidal  lobe ;  3,  3,  convolution  of  the  corpus  callosum  ;  4,  4,  convo- 
lutions forming  the  middle  group  of  the  internal  surface ;  5,  5,  convolutions  of  the 
anterior  group ;  6,  convolutions  of  the  posterior  group  ;  7,  sulcus  separating  the  mid- 
dle from  the  posterior  group ;  8,  sulcus  separating  the  anterior  and  the  middle  group ; 
9,  section  of  the  corpus  callosum;  10,  genu  of  the  corpus  callosum;  11,  rostrum  of 
the  corpus  callosum;  12,  posterior  extremity  of  the  corpus  callosum;  13,  fornix; 
14,  section  of  the  fornix ;  15,  left  anterior  crus  of  the  fornix,  passing  into  the  inter- 
nal wall  of  the  optic  thalamus,  to  reach  the  corresponding  corpus  albicans — course 
indicated  by  a  dotted  line;  16,  foramen  of  Monro;  17,  corpus  albicans,  in  which  the 
anterior  crus  of  the  fornix  bends  upon  itself,  in  the  form  of  a  figure  of  eight,  to  be 
lost  in  the  substance  of  the  optic  thalamus ;  18,  septum  lucidum ;  19,  section  of  the 
choroid  plexus  ;  20,  pineal  gland  ;  21,  left  superior  peduncle  of  the  same;  22,  sec- 
tion of  the  gray  commissure  of  the  third  ventricle  ;  23,  tubercula  quadrigemina,  above 
which  are  seen  the  pineal  gland  with  its  inferior  peduncle  and  the  posterior  com- 
missure ;  24,  section  of  the  anterior  commissure  ;  25,  aqueduct  of  Sylvius ;  26,  sec- 
tion of  the  valve  of  Vieussens ;  27,  fourth  ventricle ;  28,  28,  section  of  the  middle 
lobe  of  the  cerebellum;  29,  arbor  vitas;  30,  corpus  cinereum;  31,  pituitary  body; 
32,  optic  nerve ;  33,  pons  Varolii ;  34,  medulla  oblongata. 


I  THE   CEREBRUM. 

The  cerebrum  fills  the  anterior  and  the  middle  fossse  of  the 


26  THE  BRAIJSr. 

above  the  tentorium  cerebelli,  since  that  membrane  supports 
its  posterior  part.  Its  gray  matter  is  not  alone  confined  to  its 
exterior  surface,  where  it  covers  all  of  the  convolutions  and 
the  sulci  between  them,  but  it  is  also  present  as  two  distinct 
collections,  in  the  region  of  the  floor  of  the  brain  called  the 
corpora  striata, '  and  the  optic  thalami.  To  these  latter  col- 
lections of  gray  matter  the  term  "  hasal  ganglia  "  is  applied, 
on  account  of  their  relative  situation  within  the  substance  of 
the  cerebrum. 

While  it  will  enable  you  to  more  clearly  understand  the 
functions  of  those  parts,  concerning  which  experiment  or 
clinical  observation  has  gained  positive  knowledge,  by  study- 
ing each  of  these  basal  ganglia  apart  from  the  cerebrum,  still 
the  general  relation  of  the  component  parts  of  the  hemispheres 
will  have  to  be  first  mentioned,  in  order  to  proi)erly  appreci- 
ate the  bearing  of  facts  which  will  be  discussed  later  in  this 
chapter. 

The  gray  matter  which  covers  the  exterior  portion  of  each 
hemisphere  of  the  cerebrum  is  connected  with  white  nerve 
fibers,  which  may  be  divided  into  two  classes  ;  the  first  of 
which  can  be  traced  from  the  various  parts  of  the  exterior  of 
the  cerebrum  toward  the  basal  ganglia,  while  the  second  com- 
prise certain  curved  commissural  fibers,  which  pass  into  the 
white  substance  for  a  certain  dejith,  and  then  return  to  the 
gray  matter  of  the  surface,  thus  serving  to  connect  different 
convolutions  with  each  other.  The  first  set  mentioned  are 
called  "  converging  fibers,'''^  since  all  the  different  points  upon 
the  large  expanse  of  surface  of  the  cerebrum  send  fibers  which 
pass  through  either  the  corpus  striatum  or  the  optic  thalamus 
of  the  same  side,'  and  they  thus  present  a  converging  appear- 
ance, on  an  appropriate  section  of  the  brain  being  made.    We 

'  This  ganglion,  in  each  hemisphere,  consists  of  two  portions,  called  the  "  caudate  nu- 
cleus" and  the  "lenticular  nucleus,"  which  are  separated  from  each  other  by  the  so-called 
"  internal  capsule  "  of  the  cerebrum.  These  subdivisions  are  shown  in  Fig.  8  of  this 
volume. 

2  This  statement  is  only  approximately  correct,  since  the  internal  capsule  is  probably 
the  chief  path  for  these  fibers.  To  what  extent  the  basal  ganglia  are  directly  associated 
with  the  fibers  of  the  cortex  is,  as  yet,  an  unsolved  problem. 


FUNCTIONS  OF  CEREBRUM. 


27 


know,  from  clinical  facts  associated  with  cases  of  cerebral 
hsemorrhage  and  cerebral  softening,  that  the  cerebrum  must 
receive,  by  means  of  certain  of  these  converging  fibers,  sensory 
impressions  from  other  parts,  as  the  normal  perception  of 
external  objects  is  sometimes  destroyed  ;  while  we  also  know 
that,  in  the  same  type  of  cases,  motor  impulses  are  often  de- 
stroyed, thus  proving  that  motor  fibers  are  also  included 
among  those  which  pass  through  the  internal  capsule  or  the 
basal  ganglia.  I  think  it  can  be,  therefore,  safely  stated  that 
the  association  between  the  gray  matter  of  the  cerebrum  and 
both  the  motor  and  sensory  nerve  fibers  is  considered  as 
proven,  although  some  doubt  may  still  exist  as  to  the  precise 
course  of  these  fibers. 


Fig.  11, — Diagrammatic  representation  of  the  fibers  in  the  cerehrrim.     (Le  Bon.) 

FuiN^CTioNS  OF  THE  Cerebrum. — At  the  present  day  we 
'e  in  possession  of  a  sufficient  number  of  facts,  derived  from 


28  THE  BRAIN. 

clinical  observation,  pathological  research,  and  experimental 
investigation,  to  render  it  certain  that  no  intelligence  can  ex- 
ist without  brain  substance  ;  that  the  destruction  of  brain 
substance  impairs  intellectual  power;  and  that  the  normal 
use  of  the  brain  implies  a  degeneration  of  its  substance  and 
a  constant  process  of  regeneration,  as  exists  in  all  tissues. 

It  was  formerly  supposed  that  the  cerebrum  was  destitute 
of  both  sensation  and  irritability,  since  experiments  seemed  to 
show  that  no  pain  was  experienced  by  removal  of  portions  of 
the  hemispheres,  nor  convulsive  movements  produced  by  dii'ect 
stimulation  of  either  the  white  or  gray  matter.  It  has  there- 
fore been  claimed  that  the  hemispheres  could  be  called  into 
action  only  in  response  to  a  sensory  impression  transmitted  to 
its  cells  through  sensory  nerves,  and  that  it  was  incapable  of 
transmitting  or  appreciating  artificial  forms  of  stimulation. 
In  1870,  however,  Fritsch '  and  Hitzig  ^  discovered  that  certain 
parts  of  the  gray  matter  of  the  hemispheres  of  the  brain  of  a 
dog  responded  to  a  weak  galvanic  current,  and  these  investi- 
gators were  thus  enabled  to  locate  centers  where  certain  well- 
defined  movements  could  be  produced  at  will.  These  experi- 
menters found  (1)  that  the  centers  of  motion  were  always 
confined  to  the  anterior  parts  of  the  hemisphere  ;  (2),  that 
the  action  on  muscles  was  a  crossed  action^^  i.  e.,  on  the  side 
opposite  to  the  stimulation  ;  and  (3),  that,  after  severe  haemor- 
rhage, the  excitability  of  the  gray  matter  disappeared,,  thus 
possibly  accounting  for  the  negative  results  of  previous  ex- 
perimenters in  the  same  line. 

The  centers  of  motion  discovered  by  these  experiments 
seemed  to  be  connected  with  parts  which  were  widely  sepa- 
rated, and  arranged  with  little  apparent  system ;  thus  the 
muscles  of  the  neck  were  found  to  respond  to  galvanism  of  a 
center  in  the  middle  of  the  frontal  convolution,  while  the  cen- 

'  Reichardt  u.  du  Bois-Raymond's  "  Archiv,"  1870. 

Mlitzig,  "Das  Gchirn,"  1874. 

'  Bro\vn-S6quard  has  shown  that,  in  exceptional  eases,  this  law  may  be  not  sustained 
by  clinical  facts.  "  Lancet,"  1876.  The  anatomical  researches  of  Flechsig,  however,  tend 
to  explain  the  exceptions  to  the  general  rule  (sec  pages  of  this  volume  referring  to  the 
fibers  of  the  medulla  oblongata). 


THE  HEMISPHERES,  29 

rer  adjoining  it  caused  a  response  in  the  extensor  and  abduc- 
tor muscles  of  the  fore-leg,  and  others  in  movements  of  the 
eye  and  face.  Ferrier'  has  of  late  repeated  and  confirmed 
i\\e  experiments  of  these  German  investigators/ 

The  effects  of  removal  of  the  cerebral  hemispheres  of  ani- 
mals have  been  studied  largely  upon  birds  and  the  monkey 
tribe,  and  with  results  which  are  comparatively  uniform. 
Without  entering  into  detail  as  to  all  the  effects  which  follow 
such  a  procedure,  in  case  the  basal  ganglia  are  left  intact,  the 
o-eneral  result  may  be  given  as  follows  :  The  animal  seems  to 
be  able  to  execute  all  the  movements  natural  to  it,  even  when 
(^omplex  coordination  of  movement  is  required  ;  but  the  intel- 
ligence seems  to  be  impaired,  and  some  unusual  stimulus  must 
be  present  to  prompt  any  attempts  at  motion.  As  a  result  of 
this  conclusion,  the  mechanism  of  coordination  of  movement 
is  evidently  not  situated  in  the  cerebral  hemispheres. 

Flourens,'  from  a  series  of  experiments  made  in  1822  and 
1823,  concluded  that  the  removal  of  the  cerebrum  entailed  an 
entire  loss  of  will  power  and  also  of  the  perceptive  faculty, 
and  that  the  memory  was  utterly  destroyed.  Bouillaud,*  in 
1826,  proved  the  error  of  Flourens  as  regards  the  perceptive 
faculties,  as  sight  and  hearing  were  shown  to  be  unaffected  ; 
and  these  results  were  still  further  made  manifest  by  the  re- 
searches of  Longet,'  who  proved  also  that  taste  remained. 

A  careful  study  of  the  phenomena  which  accompany  cer- 
tain pathological  lesions  of  the  brain  in  the  human  subject, 
such  as  laceration  or  pressure  from  the  effusion  of  blood,  soft- 
ening of  the  cerebral  substance,  etc.,  if  taken  in  connection 
with  the  results  of  experiments  upon  living  animals,  throws 
considerable  light  upon  the  functions  of  certain  distinct  por- 
tions of  the  encephalon. 


'  "West  Riding  Reports,"  1873  ;  "  Functions  of  the  Brain,"  1876. 

^  A  large  number  of  distinct  centers  of  motion  are  mapped  out  by  this  author  on  a 
diagrammatic  chart.     The  reader  is  referred  to  Fig.  15  of  this  volume. 

^"Rocherches  experimentales  sur  les  proprietes  et  les  fonctionsdu  systemc  nerveux,'* 
Paris,  1842. 

*  "  Recherches  experimentales  sur  les  fonctions  du  cerveau." 

^  "Anatomic  et  physiologic  du  systeme  nerveux,"  Paris,  1842. 


30  THE  BRAIN. 

HcBmorrhage  within  the  brain  substance  most  commonly 
affects  the  corpus  striatum  or  the  optic  tJialamus  ;  and  it  is 
now  considered  probable  that,  when  the  former  ganglion  is 
pressed  upon,  paralysis  of  motion^  limited  to  the  side  of  the 
body  opposite  to  the  lesion,  is  present,  while,  if  the  latter 
ganglion  is  pressed  upon  or  destroyed,  the  sensation  of  the 
side  of  the  body  opposite  to  the  lesion  is  proportionally 
impaired.'  These  facts  illustrate  the  general  course  of  both 
the  motor  and  sensory  fibers  through  the  cerebrum,  and  their 
relation  to  the  basal  ganglia  or  the  internal  capsule. 

In  those  exceptional  cases  of  haemorrhage  where  the  white 
or  the  gray  substance  of  the  cerebral  hemispheres  is  alone 
involved,  without  any  pressure  being  exerted  upon  the  basal 
ganglia  or  the  internal  capsule,  no  paralysis  of  either  motion 
or  sensation  is  usually  produced,  although  a  certain  amount 
of  weakness  may  often  be  perceived  in  the  muscles  of  the 
side  of  the  body  opposite  to  the  seat  of  the  haemorrhage. 

Softening  of  the  cerebral  hemispheres  and  the  degenera- 
tive changes  which  often  follow  an  extravasation  of  blood 
into  their  substance  are  generally  indicated  by  alterations  in 
the  intellectual  condition  of  the  patient,  thus  confirming  the 
physiological  experiments  upon  the  hemispheres.  Among 
the  many  forms  in  which  this  impairment  of  intellect  may 
be  manifested  are  recognized  an  impairment  of  memory  ;  a 
tardy,  inaccurate,  and  feeble  connection  of  ideas  ;  an  irritabili- 
ty of  temper,  with  a  childish  susceptibility  to  petty  or  imagi- 
nary annoyances ;  easily  excited  emotional  manifestations ; 
and  a  variety  of  phenomena  denoting  abnormally  feeble  in- 
tellectual power.' 

Hughlings- Jackson '  has  shown  that  there  is  clear  evidence 
to  prove  that  disease  of  the  gray  matter  of  the  convolutions  of 
the  hemispheres  of  the  cerebrum  may  not  only  produce  de- 
lirium^ as  in  meningitis,  but  sometimes  convulsioiis.  either  of 

*  This  effect  on  sensation  and  motion  is  explained  by  some  authors  as  tlie  result 
of  pressure  upon  the  fibers  of  the  intci'nal  capsule,  and  not  the  fibers  of  the  basal 
ganglia. 

'  A.  Flint,  Jr.,  op.  cit. 

»  "London  Hosp.  Reports,"  18G4  ;  "  Clin,  and  Phys.  Researches,"  1873. 


CENTERS  OF  MOTION 


31 


an  epileptiform  character  or  confined  to  particular  groups  of 
muscles. 

Landois '  and  Hitzig '  both  announced  the  fact  that,  when 
the  motor  areas  upon  the  convex  surface  of  the  cerebrum, 


Fig.  12. — A  diagrammatic  fgure,  showing  the  cerebral  convolutions.     (After  Dalton.) 


S,  Fissure  of  Sylvius,  with  its  two  branches  a  and  h,  b,  b  ;  R,  fissure  of  Rolando ;  P,  pa- 
rieto-occipital  fissure;  1,  1,  1,  the  first  or  superior  frontal  convolution;  2,  2,  2,  2, 
the  second  or  middle  frontal  convolution ;  3,  3,  3,  the  third  frontal  convolution, 
curving  around  the  ascending  limb  of  the  fissure  of  Sylvius  {center  of  speech) ;  4,  4, 4, 
ascending  frontal  (anterior  central)  convolution  ;  5,  5,  5,  ascending  parietal  (pos- 
terior central)  convolution ;  6,  6,  6,  supra-Sylvian  convolution  (parietal  lobule), 
which  is  continuous  with  7,  7,  7,  the  first  or  superior  temporal  convolution  ;  8,  8,  8, 
the  angular  convolution  (or  gyrus),  the  probable  center  of  vision^  which  becomes 
continuous  with  9,  9,  9,  the  middle  temporal  convolution;  10,  the  third  or  in- 
ferior temporal  convolution ;  11,  11,  the  superior  parietal  (supra-marginal)  convo- 
lution; 12,  12,  12,  the  superior,  middle,  and  inferior  occipital  convolutions  (called 
also  the  first,  second,  and  third).  It  is  to  be  remembered  that  the  term  "  gyrus  "  is 
synonymous  with  convolution,"  and  that  both  terms  are  often  interchanged.  This 
cut  may  well  be  compared  with  that  of  Ferrier,  which  appears  in  the  general  sum- 
mary of  the  clinical  points  of  the  brain. 

which  control  the  movements  of  the  extremities,  are  excised, 
^rise  in  the  temperature  of  the  corresponding  limbs  takes 


Virchow's  "Archiv,"  1876. 
As  quoted  by  Foster. 


32  TEE  BRAIN. 

place  and  lasts  for  some  months.  A  relationship  has,  more- 
over, been  observed  between  the  brain  cortex  and  the  beat  of 
the  heart  (Balogh ') ;  an  alteration  in  the  arterial  pressure 
(Bochefontaine ') ;  contraction  of  the  bladder,  spleen,  and 
uterus ;  an  increase  in  the  flow  of  the  saliva ;  and  a  dilating 
effect  upon  the  pupil.  The  exact  localization  of  some  of  these 
latter  centers  can  not,  as  yet,  be  considered  as  positive. 

Stimulation  of  the  cerebral  surface  has  been  observed  to 
result  in  a  well-marked  hcemorrhage  of  the  lungs  by  Noth- 
nagel.' 

Ferrier*  describes  a  ''msuaV  center,  the  destruction  of 
which  creates  blindness  of  the  opi)osite  eye  ;  an  "-auditory" 
center;  a  ''tactile''^  center;  centers  for  smell  and  taste;  and 
even  a  center  for  the  sensation  of  hunger. 

The  center  of  articulate  speech  is  perhaps  one  of  the  most 
definitely  settled  points  in  cerebral  localization ;  and  this  is 
all  the  more  interesting,  since  this  is  the  only  sharply  defined 
faculty  which  has,  as  yet,  been  definitely  localized.'  There 
are  two  forms  of  aphasia,  which  are  clinically  recognized,  viz., 
the  amnesic  and  the  ataxic  varieties.  In  the  former,  the 
m^emory  of  words  is  utterly  lost,  so  that  the  patient  is  not 
only  unable  to  express  his  ideas  in  articulate  sounds,  but  he  is 
also  unable  to  write  them,  thus  showing  that  the  words  them- 
selves have  been  forgotten.  In  the  ataxic  variety,  however, 
the  memory  of  words  still  remains,  but  the  ability  to  so  coordi- 
nate the  muscles  of  articulation  as  to  pronounce  the  words  is 
impaired,  so  that  the  person  so  afflicted  can  vrrite  his  ideas 
intelligently,  but  can  not  utter  them.  In  either  of  these  con- 
ditions, the  disease  which  causes  it  must  affect  the  center  of 
the  muscles  of  articulate  speech  or  the  center  of  articulate 
speech  itself.  It  is  not  to  be  confounded,  however,  with 
other  diseases  where  the  ability  to  talk  is  apparently  absent, 
such  as  occurs  in  the  insane  (who  often  refuse  to  converse 
from  mere  obstinacy),  in  those  types  of  paralysis  which  affect 

'  Hofmann  und  Schwalbe's  "  Bericht,"  1876.        "^  "  Archives  dc  Physiol.,"  1876. 
3  "Cbl.  med.  Wiss.,"  1874.  ■•  Op.  cit. 

'  Some  late  authors  refuse  their  concurrence  with  this  statement,  as  several  cases  have*^ 
been  reported  which  tend  to  justify  a  doubt  as  to  its  accuracy. 


CENTER   OF  SPEECH.  33 

the  entire  muscular  mechanism  associated  with  articulation, 
in  hysteria,  chorea,  and  nervous  affections,  and  in  the  apho- 
nia of  laryngeal  inflammation  or  paralysis. 

The  credit  of  the  great  discovery  that  the  center  of  articu- 
late speech  could  be  localized  in  the  third  convolution  of  the 
left  anterior  lohe  of  the  cerebrum  is  generally  awarded  to 


Fig.  13. — Structure  of  the  convolutions.     (After  Baillarger.) 

1,  the  six  alternate  gray  and  white  layers  in  the  cortical  substance  of  the  convolutions; 
2,  enlarged  section  of  a  convolution — the  left  half  is  seen  by  reflected  light — layers 
arranged  as  in  the  preceding  figure — in  the  right  half,  seen  by  transmitted  light,  the 
medullary  layers  are  rendered  dark  by  their  opacity — the  layers  of  gray  substance,  on 
the  other  hand,  which  are  translucent,  are  represented  in  white ;  3,  section  of  a  con- 
volution showing  the  unequal  thickness  of  the  white  layers — at  first  sight  only  three 
layers  can  be  distinguished,  two  gray  and  an  intervening  white  layer — more  attentive 
examination  shows  six  layers,  the  superficial  and  deep  white  layers  being,  however, 
very  narrow ;  4,  section  of  a  convolution  showing  the  three  layers  of  gray  matter 
observed  by  Vicq  d'Azyr  in  the  occipital  lobe ;  5,  tendency  to  radiation  shown  by  the 
white  fibers  in  the  gray  matter  of  the  convolutions ;  6,  section  of  a  cerebral  convolu- 
tion in  a  newly  born  infant,  seen  by  reflected  light — it  presents  an  homogeneous 
appearance ;  7,  same  section  seen  by  transmitted  light — presents  the  same  stratifica- 
tion and  tendency  to  radiation  which  are  observed  in  the  adult. 

Broca.'  Some  twenty-five  years  before  he  made  the  profession 
alive  to  the  investigation  of  the  subject,  however,  the  same 
impairment  or  loss  of  speech  was  shown  to  be  a  frequent 
accompaniment  of  hemiplegia  of  the  right  side  of  the  body  by 
Bouillaud  and  Marc  Dax ' ;  and  in  1863,  or  thereabout,  the 


I 


J  Broca,  "Bui.  de  la  Soc.  Anat.,"  1861. 

'  A  paper  read  before  the  Medical  Congress  at  I^Iontpellier  in  1836. 


34  THE  BRAIN. 

views  of  Broca  and  of  Hughlings- Jackson '  were  given  to  the 
profession,  in  which  they  both  limited  the  lesion  of  aphasia 
to  the  parts  supplied  by  the  left  middle  cerebral  artery.  In 
1863,  the  investigations  also  of  the  son  of  Marc  Dax "  located 
the  lesion  somewhere  in  the  anterior  or  middle  portion  of  the 
frontal  lohe  of  the  left  side,  and  the  results  of  still  more 
recent  investigations  upon  the  subject  seem  to  point  to  the 
"island  of  Reil"  as  the  most  frequent  seat  of  this  peculiar 
type  of  paralysis. 

Viewing  the  fact  that  articulate  speech  is  a  thing  learned 
by  use,  it  has  been  suggested  that,  in  most  persons,  one  side 
of  the  brain  only  has  been  educated  for  that  purpose ;  that 
we  are,  in  fact,  left-hrained  in  respect  to  speech  in  the  same 
way  that  we  are  right-handed  in  respect  to  many  bodily 
movements."*  In  support  of  this  theory  the  pathological 
fact  is  adduced  that,  in  most  people,  the  left  hemisphere 
of  the  cerebrum  is  larger  and  more  convoluted  than  the 
right. 

While  it  is  demonstrated  that  the  cerebral  lesion  in  apha- 
sia involves,  in  the  great  majority  of  cases,  the  left  side,  still 
there  have  been  several  cases  recorded  where  the  right  side 
has  been  shown  to  have  been  the  seat  of  disease.*  Such  dis- 
coveries tend  to  cast  a  doubt  upon  the  left  side  being  more 
closely  connected  with  the  power  of  articulate  speech  than  the 
right  side,  and  some  anatomists  have  endeavored  to  explain 
the  frequency  of  the  lesion  upon  the  left  side  of  the  brain  as 
a  result  of  the  fact  that  emboli  (which  are  the  most  frequent 
cause  of  the  disturbance  to  those  parts  supplied  by  the  middle 
cerebral  artery)  find  a  much  more  direct  course  upward  upon 
the  left  side  than  upon  the  right,  in  consequence  of  the  angle 
at  which  the  innominate  artery  leaves  the  arch  of  the  aorta, 
which  favors  the  passage  of  an  embolus  hy  rather  than  into 
its  mouth ;  while  the  left  carotid  artery  is  situated  at  the 

'  Hughlings-Jackson,  "  Clinical  and  Physiological  Researches  on  the  Nervous  Sys- 
tem." 

'  M.  G.  Dax,  as  quoted  by  Dodds  and  A.  Flint,  Jr. 

'  Mich.  Foster,  op.  cif.  ;  Ferrier,  "  Functions  of  the  Brain." 

*  Boyd,  Broadbent,  Bateman,  Meissner,  Bertin. 


THE  FRONTAL  LOBES. 


35 


highest  part  of  the  arch,  and  its  mouth  is  so  directed  as  to 
arrest  rather  than  avoid  any  floating  particles  in  the  blood 
current.  In  case  of  such  movable  particles  being  arrested 
either  by  the  innominate  or  left  carotid  arteries,  the  most 
direct  course  in  both  instances  will  be  toward  the  middle  cere- 
bral arteries,  and  thus  aphasia  will  generally  be  produced 
with  hemiplegia  upon  the  side  opposite  to  that  where  the 
embolus  may  be  found. 

The  Frontal  Lobes. — There  are  innumerable  cases  on 
record  where  the  frontal  lobes  of  the  cerebrum  have  suffered 


MEDULLA 

Fig.  U. — Diagram  of  the  course  of  sensory  arid  motor  tracts  in  the  meso-cephalon  and 
hemispheres.     (After  Seguin.) 

S,  sensory  tract  in  posterior  region  of  meso-cephalon,  extending  to  0  and  T,  occipital 

and  temporal  lobes  of  hemispheres  ;  M,  motor  tract  in  basis  cruris,  extending  to  P 

and  F,  parietal  and  (part  of)  frontal  lobes  of  hemispheres ;  C,  Q,  corpus  quadrigemi- 

HL  num ;  0,  T,  optic  thalamus ;  N,  L,  nucleus  Icnticularis ;  N,  C,  nucleus  caudatus  ;  1, 

IH  the  fibers  forming  the  "  tegmentum  cruris "  (Meynert) ;  2,  the  fibers  forming  the 

■■[  "  basis  cruris  "  (Meynert). 

^frightful  lacerations  and  loss  of  substance,  and  yet  recovery 
\  has  taken  place  ;  and  where  disease  of  an  extensive  character 
I  has  also  produced  negative  results,  both  as  regards  motion  and 
sensation. 


36  THE  BRAIN. 

A  crowbar  has  been  shot  through  the  head,  and  recovery 
followed. '  Again,  Bouillaud '  reports  the  passage  of  a  bullet 
through  the  frontal  lobes  with  a  like  result,  and  with  no  effect 
upon  sensation  or  motion.  Cases,  somewhat  similar,  are  re- 
corded by  Trousseau,' Congreve,  Selwyn,*  Pitres,"  Morgagni, 
Marot,"  Tavignot,  and  others,  all  of  which  go  to  x^rove  the  pos- 
sibility of  the  most  serious  injury  to  this  portion  of  the  cere- 
brum without  symptoms  indicative  of  its  presence.  On  the 
other  hand,  numerous  cases  of  haemorrhage  and  of  abscess 
within  the  frontal  lobes,  as  reported  by  Andral,'  Hertz,  Reed, 
Begbie,  and  others  (quoted  by  Charcot  and  Ferrier),  show  the 
same  absence  of  positive  diagnostic  symptoms  either  in  sen- 
sory or  motor  paralysis. 

From  such  sources  of  clinical  reasoning,  as  well  as  from  the 
physiological  deductions  which  experiments  upon  animals 
have  taught,  the  following  conclusion  of  Ferrier  *  is  of  value  to 
the  reader :  ''  With  such  evidence  before  us,  we  can  not  regard 
cases,  in  which,  with  lesions  of  the  prsefrontal  lobes,  sensation 
or  motion  has  been  affected,  as  other  than  cases  of  coexistence 
or  of  multiple  lesions,  whether  organic  or  functional." 

THE  MOTOR  REGIONS  OF  THE  CEREBRUM." 

It  may  now  be  positively  stated  that  the  bases  of  the  three 
frontal  convolutions,  the  convolutions  which  bound  the  fis- 

^  Bigelow,  "Am.  Jour,  of  Med.  Sciences,"  July,  1850;  Harlow,  "Recovery  from  the 
Passage  of  an  Iron  Bar  through  the  Head  "  ;  "  Reports  of  Mass.  Med.  Soc,"  Boston,  1869. 

2  Op.  cit. 

2  Quoted  by  Peter  and  Ferrier. 

4  London  "  Lancet,"  183 S. 

^  "  Lesions  du  Centre  Ovale,"  1877. 

«  "Prog.  M6d.,"  February  and  June,  1876. 

'  "  Clinique  M6dicale." 

"  "Localization  of  Cerebral  Disease,"  New  York,  1880. 

®  Microscopic  anatomy  shows  that  the  so-called  motor  gyri  are  rich  ^in  large  cells ; 
that  they  alone  contain  the  "giant  cells"  of  Betz  ("  Centralblatt,"  Nos.  37,  38),  viz., 
ganglion  cells,  which  in  size  and  number  of  processes  bear  a  remarkable  resemblance  to 
the  unquestionably  motor  ganglion  cells  of  the  anterior  horns  of  the  spinal  cord  and  the 
medulla  oblongata.  In  the  motor  convolutions  these  giant  cells  are  found  in  little  clus- 
ters of  three,  five,  or  more,  in  a  section,  imbedded  among  the  large  ganglion  cells  of  the 
third  layer. 


TEE  MOTOR  AREA.  37 

Hwre  of  Rolando^  and  Xh^  para-central  lobule^  upon  the  inter- 
nal surface  of  each  hemisphere  of  the  cerebrum,  are  distinctly 
motor  in  their  function.  The  distribution  of  the  middle  cere- 
l)ral  artery  to  this  region  gives  to  that  vessel  an  importance 
not  before  appreciated ;  since  it  is  now  known  that  the  four 
or  five  branches  which  are  given  oif  from  the  main  artery 
each  nourish  a  separate  area  of  brain  substance,  and  that 
emboli  may  obstruct  either  the  trunk  or  some  of  its  in- 
dividual branches.  It  is  thus  possible  to  explain  how  the 
basal  ganglia  may  still  perform  their  functions  while  other 
parts  giipplied  by  some  of  the  cortical  branches  may  be  im- 
])aired. 

The  preponderance  of  clinical  testimony  goes  to  show 
that  most  of  the  destructive  lesions  which  are  associated 
during  life  with  paralysis  of  voluntary  motion  are  con- 
fined to  this  motor  area,  although  a  rare  case  is  on  re- 
cord '  where  the  motor  area  was  the  seat  of  cystic  disease, 
and  still  voluntary  motion  remained  unaffected.  It  is  a 
matter  of  great  doubt  whether  the  gray  matter  of  the  con- 
\'olutions  was  impaired,  even  in  this  case,  in  spite  of  the 
existing  lesion. 

The  effect  of  extensive  lesions  affecting  the  motor  area 
of  the  monkey  (which  is  commonly  used  for  experiments, 
as  the  nearest  approach  to  the  type  of  mankind)  may  be 
summarized  as  follows:  1.  A  hemiplegia,  which  is  at  first 
absolute ;  2.  An  improvement  in  associate,  alternating,  or 
bilateral  movements,  but  no  improvement  in  voluntary  mo- 
tion. 

Respecting  this  point,  I  quote  from  a  late  work  as  fol- 
lows: 

''As  examples  of  the  improvement  which  follows  the  on- 

I'l  set  of  the  hemiplegia,  the  hand  becomes  more  paralyzed  than 

the  arm,  the  arm  more  than  the  leg,  and   the  lower  facial 

movements  more  than  the  upper;  while  the  muscles  of  the 

I  trunk  are  scarcely,  if  at  all,  affected."  ' 


li 


^  Samt,  "Archiv  fur  Psychiatric,"  1S74. 
'  Ferrier,  ''  Localization  of  Cerebral  Disease. 


38  THE  BRAIK 

In  man  the  hemiplegia  is  usually  on  the  side  opposite  to 
the  existing  lesion/  if  the  motor  area,  the  corpus  striatum, 
or  the  anterior  part  of  the  internal  capsule  be  the  seat  of 
disease ;  and  this  paralysis  is  often  accompanied  by  con- 
vulsive muscular  movements  or  rigidity  of  the  paralyzed 
parts,  in  its  early  stage,  and,  later  on,  by  rigidity  and  motor 
sclerosis.'' 

The  researches  of  Pitres '  have  shown  that  the  same  re- 
sults as  those  dependent  upon  a  lesion  of  the  gray  matter  of 
the  convolutions  within  the  motor  area  follow  when  the  lesion 
affects  the  white  substance  of  the  brain*  which  intervenes 
between  the  gray  matter  covering  the  motor  area  and  the  basal 
ganglia  beneath  them,  and  he  thus  urges  a  system  of  nomen- 
clature of  the  different  portions  of  the  ''centrum  ovale"  by 
means  of  sections  of  the  brain  made  in  certain  regions  so  as  to 
show  special  parts. 

It  is  by  means  of  these  researches  that  we  are  enabled  to 
explain  those  cases  where  rigidity  or  muscular  spasms  accom- 
pany an*  attack  of  hemiplegia,  from  an  effusion  into  the 
lateral  ventricles  of  the  brain ;  and  where  cerebral  soft- 
ening or  hcemorrhage^  which  does  not  affect  the  gray  mat- 
ter of  the  convolutions  or  the  basal  ganglia,  produces  a  jDer- 
manent  paralysis  of  the  side  of  the  body  opposite  to  the  lesion. 

When  sudden  hemiplegia  occurs,  as  a  result  of  haemor- 
rhage into  or  traumatism  of  some  portion  of  the  motor  area, 
the  condition  of  paralysis  is  liable  to  improve  in  those  re- 
gions of  the  body  where  the  special  motor  center  of  that  part 
remains  unimpaired,  but  the  paralysis  will  usually  remain 
permanent  in  that  part  of  the  body  whose  motor  center  is 
destroyed.  This  fact,  when  properly  interpreted,  may  often 
prove  a  most  valuable  guide  in  diagnosis. 

'  The  fact  that  all  the  motor  fibers  do  not  decussate  in  the  medulla  oblongata  (Flech- 
sig)  explains  the  exceptions  to  this  rule. 

'  See  later  pages  of  this  volume  for  further  explanation  of  this  point  and  its  clinical 
interest. 

'  "Lesions  du  Centre  Ovale,"  Paris,  1877. 

*  This  portion  contains  the  fibers  of  the  into-nal  capsule  radiating  to  reach  the  motor 
regions  of  the  cortex.     (See  Fig.  8.) 


THE  MOTOR  AREA,  39 

Special  Centers  of  Motion. — At  the  base  of  the  first  fron- 
tal convolution^  and  extending  slightly  into  the  second  fron- 


I'lG.  15. — Sid?  vieio  of  the  brain  of  man  and  the  areas  of  the  cerebral  convolutions.     (After 

Ferrier.) 

(on  the  postero-parietal  [superior  parietal]  lobule),  advance  of  the  opposite  hind-limb 
as  in  walking ;  2,  8,  4  (around  the  upper  extremity  of  the  fissure  of  Rolando),  com- 
plex movements  of  the  opposite  leg  and  arm,  and  of  the  trunk,  as  in  swimming ; 
rt,  6,  c,  d  (on  the  postero-parietal  [posterior  central]  convolution),  individual  and 
combined  movements  of  the  fingers  and  wrist  of  the  opposite  hand  :  prehensile  move- 
ments ;  5  (at  the  posterior  extremity  of  the  superior  frontal  convolution),  extension 
forward  of  the  opposite  arm  and  hand  ;  6  (on  the  upper  part  of  the  antero-parietal 
or  ascending  frontal  [anterior  central]  convolution),  supination  and  flexion  of  the 
opposite  fore-arm  ;  7  (on  the  median  portion  of  the  same  convolution),  retraction  and 
elevation  of  the  opposite  angle  of  the  mouth  by  means  of  the  zygomatic  muscles  ;  8 
(lower  down  on  the  same  convolution),  elevation  of  the  ala  nasi  and  upper  lip  with 
depression  of  the  lower  lip,  on  the  opposite  side ;  9,  10  (at  the  inferior  extremity  of 
the  same  convolution,  Broca's  convolution),  opening  of  the  mouth  with  9,  protrusion, 
and  10,  retraction  of  the  tongue — region  of  aphasia,  bilateral  action;  11  (between 
10  and  the  inferior  extremity  of  the  postero-parietal  convolution),  retraction  of  the 
opposite  angle  of  the  mouth,  the  head  turned  slightly  to  one  side  ;  12  (on  the  poste- 
rior portions  of  the  superior  and  middle  frontal  convolutions),  the  eyes  open  widely, 
the  pupils  dilate,  and  the  head  and  eyes  turn  toward  the  opposite  side  ;  13,  13  (on 
the  supra-marginal  lobule  and  angular  gyrus),  the  eyes  move  toward  the  opposite  side 
with  an  upward  13,  or  downward  13*  deviation  ;  the  pupils  generally  contracted  (cen- 
ter of  vision) ;  14  (of  the  infra-marginal,  or  superior  [first]  temporo-sphenoidal  con- 
volution), pricking  of  the  opposite  ear,  the  head  and  eyes  turn  to  the  opposite  side, 
and  the  pupils  dilate  largely  (center  of  hearing).  Ferrier,  moreover,  places  the  cen- 
ters of  taste  and  smell  at  the  extremity  of  the  temporo-sphenoidal  lobe,  and  that  of 
touch  in  the  gyrus  uncinatus  and  hippocampus  major. 


40  TEE  BRAIK 

tal  convolution^  in  the  brain  of  a  monkey  may  be  located  a 
distinct  center  which  exerts  a  special  influence  upon  the  head 
and  eyes.  Thus,  to  qiiote  from  Ferrier,  whose  researches 
have  been  remarkable  for  their  originality  and  apparent  accu- 
i*acy,  stimulation  of  this  center  causes  ' '  elevation  of  the  eye- 
lids^ dilatation  of  the  pupils^  conjugate  deviation  of  iJie 
eyes^  and  turning  of  the  head  toward  the  opposite  side^ 
(See  JSTo.  12  in  Fig.  15.) 

That  this  same  center  seems  to  exist  in  the  human  brain  is 
to  be  inferred  from  the  cases  where  a  h Hater al  deviation  of 
the  eyes  has  been  observed,  w^hich,  in  some  cases,  has  also 
been  associated  with  a  lateral  deflection  of  the  head.  Tliis 
subject  has  excited  the  interest  of  Hughlings- Jackson, '  Priest 
ley  Smith,"  Ferrier,'  and  Charcot,*  and  cases  which  seem  to 
sustain  the  theory  of  an  oculo-motor  function  in  the  frontal 
convolutions  have  been  reported  by  Chouppe,  Landouzy,' 
Carroll,  Smith,  and  others.  An  effort  has  been  made  to  ex- 
plain these  ocular  symptoms  by  some  association  with  the 
angular  gyrus  (see  page  52),  but  apparently  without  much 
ground. 

The  center  of  motion  for  the  muscles  of  the  limbs  is  not 
yet  as  positively  ascertained  as  the  oculo-motor  center,  al- 
though some  interesting  experiments  have  been  made  to  de- 
cide whether  the  corresponding  point  of  the  brain  of  man  is 
analogous,  in  its  control  over  the  leg,  to  that  of  the  monkey 
tribe.  As  an  example  of  the  ingenuity  shown  in  research, 
Bourdon"  has  endeavored  to  demonstrate  atrophy  of  certain 
parts  of  the  brain  after  amputation  of  the  limbs,  and  thus 
indirectly  to  prove  the  normal  use  of  the  parts  which  had 
atrophied  from  disuse.  The  use  to  which  the  monkey  puts 
his  tail,  since  it  serves  the  purpose  of  an  additional  hand  in 
some  instances,  renders  the  application  of  movements  of  that 

'  "Ophthalmology  in  its  Relations  to  General  Medicine,"  "Lancet,"  1877. 
"  "Bilateral  Deviations  of  the  Eyes,"  "Birmingham  Med.  Beview,"  1875. 
»  Op.  cit. 

•  Op.  cit, 

•  "  BlC-pharoptose  cer6bralc,"  "  Arch.  Gen.  de  MedV  1877. 

•  "  Recherches  cliniques  sur  les  centres  moteurs,"  Paris,  1877. 


SPECIAL    CENTERS  OF  MOTION, 


41 


Pig.  16. —  Upper  view  of  the  brain  of  man.  and  tJve  situation  of  areas  of  live  cei'^ral  con- 
volutions. (After  Ferrier.) 
I  (on  the  postero-parietal  [superior  parietal]  lobule),  advance  of  the  opposite  hind- 
limb  as  in  walking;  2,  a,  4  (around  the  upper  extremity  of  the  fissure  of  Rolando), 
complex  movements  of  the  opposite  leg  and  arm,  and  of  the  trunk,  as  in  swim- 
ming ;  a,  b,  c,  d  (on  the  postero-parietal  [posterior  central]  convolution),  indi- 
vidual and  combined  movements  of  the  fingers  and  wrist  of  the  opposite  hand ;  pre- 
nsile  movements ;  5  (at  the  posterior  extremity  of  the  superior  frontal  convolu- 
n),  extension  forward  of  the  opposite  arm  and  hand ;  6  (on  the  upper  part  of 
antero  parietal  or  ascending  frontal  [anterior  central]  convolution),  supination 
d  flexion  of  the  opposite  forearm ;  7  (on  the  median  portion  of  the  same  con- 
lution),  retraction  and  elevation  of  the  opposite  angle  of  the  mouth  by  means  of 
zygomatic  muscles ;  8  (lower  down  on  the  same  convolution),  elevation  of 
e  ala  nasi  and  upper  lip  with  depression  of  the  lower  lip,  on  the  opposite  side ;  9, 
(at  the  inferior  extremity  of  the  same  convolution,  Broca's  convolution),  open- 
^  of  the  mouth  with  9,  protrusion,  and  10,  retraction  of  the  tongue — region  of 
hasia,  bilateral  action;  11  (between  10  and  the  inferior  extremity  of  the  pos- 
parietal  convolution),  retraction  of  the  opposite  angle  of  the  mouth,  the  head 
med  slightly  to  one  side  ;  12  (on  the  posterior  portions  of  the  superior  and  mid- 
le  frontal  convolutions),  the  eyes  open  widely,  the  pupils  dilate,  and  the  head  and 
«s  turn  toward  the  opposite  side  ;  13,  13  (on  the  supra-marginal  lobule  and  an- 
lar  gyrus),  the  eyes  move  toward  the  opposite  side  with  an  upward  13,  or  down- 
rd  13-  deviation — the  pupils  generally  contracted  (center  of  vision) ;  14  (of 
e  infra-marginal,  or  superior  [first]  temporo-sphenoidal  convolution),  pricking  of 
e  opposite  ear,  the  head  and  eyes  turn  to  the  opposite  side,  and  the  pupils  dilate 
anrely  (center  of  hearing).  Ferrier,  moreover,  places  the  centers  of  taste  and  smell 
at  the  extremity  of  the  temporo-sphenoidal  lobe,  and  that  of  touch  in  the  gyrus  un- 
cinatus  and  hippocampus  major. 


42  TEE  BRAIN. 

organ  to  those  of  man  a  matter  of  apparent  difficulty,  and  the 
center  of  motion  for  the  tail  of  the  monkey  can  hardly  be 
applied  to  the  brain  of  man  without  bringing  comparative 
anatomy  into  prominence. 

Paralysis  of  the  leg,  when  dependent  solely  upon  cerebral 
lesions,  is  seldom  separated  from  a  similar  condition  of  the 
upper  extremity,  although  a  few  rare  cases  of  that  character 
are  on  record  ;  but  the  rule  of  Lucas  Championniere  may  be 
considered  as  approximately  correct,  viz.,  that,  to  expose  the 
center  of  motion  for  the  muscles  of  the  leg,  it  is  necessary 
to  trephine  over  the  upper  extremity  of  the  fissure  of 
Rolando  ."^ 

The  centers  of  motion  for  the  muscles  of  the  different  re- 
gions of  the  upper  extremity  occupy  a  much  larger  space 
upon  the  surface  of  the  cerebrum  than  those  of  the  lower  ex- 
tremity, as  might  have  been  expected  when  we  consider  the 
amount  of  intelligence  which  the  hand  exhibits.'  Ferrier 
has  pointed  out  certain  motor  areas  for  the  various  move- 
ments of  extension,  adduction  and  retraction,  supination  and 
flexion,  and  centers  for  the  actions  of  the  wrist  and  finger 
muscles.' 

The  close  proximity  of  those  centers  which  control  the/a- 
cial  and  oral  muscles  to  the  centers  governing  the  motions  of 
the  hand  possibly  explains  why  movements  of  retraction  of 
the  mouth  occur  when  the  hand  is  brought  into  powerful 
action ;  and  also  the  fact  that  paralysis  of  certain  groups  of 
muscles  situated  in  the  upper  extremity  are  commonly  asso- 
ciated with  some  form  of  facial  paralysis. 

From  a  careful  analysis  of  cases  where  paralysis  of  the  up- 
per extremity  was  confined  to  certain  sets  of  muscles,  the  re- 
sults seem  to  point  to  the  ascending  parietal  and  the  upper 


'  For  the  surgical  guide  to  locate  the  situation  of  that  fissure  upon  the  exterior  sin- 
faee  of  the  skull  of  a  living  subject,  the  reader  is  referred  to  a  subsequent  page  of  this 
chapter. 

»  Sir  Charles  Bell,  "  The  Human  Hand." 

'  In  pages  39  and  41  of  this  volume,  the  centers  of  Ferrier  are  shown  in  a  dia- 
grammatic cut,  and  the  special  action  of  each  given  in  the  descriptive  text  which  accom- 
panies it. 


SPECIAL    CENTERS  OF  MOTION.  43 

loortion  of  the  ascending  frontal  convolutions  of  the  cere- 
brum, as  the  probable  seat  of  disease  ;  and  lesions  of  the 
ascending  parietal  convolution  are  found,  both  by  experi- 
mental research  and  by  pathological  deduction,  to  affect 
the  hand  in  particular.  In  further  support  of  this  state- 
ment, the  results  of  the  examination  of  the  brains  of  per- 
sons who  had  suffered  amputation  of  the  hand, '  or  who 
had  been  characterized  by  a  congenital  absence  of  that 
member,''  show  an  atrophy  of  the  part  designated  by  the 
experiments  of  Ferrier  as  the  motor  center  for  its  move- 
ments. 

The  motor  centers  of  th.^  facial  muscles  occupy  a  region  in 
close  proximity  to  those  of  the  arm  and  hand  ;  and  it  is  an 
exception  to  the  general  rule  to  observe  paralysis  confined 
exclusively  to  the  face,  since  the  muscles  of  some  part  of  the 
upper  extremity  are  generally  affected  simultaneously.  It  may 
be  also  noticed,  with  some  degree  of  practical  interest,  that 
aphasia  is  a  common  associate  of  either  of  these  types  of  local- 
ized paralysis,  since  the  center  of  Broca  is  liable  to  be  also  in- 
volved from  its  close  relation  to  both  the  centers  of  the  face, 
arm,  and  hand.'  It  is  considered  by  some  authorities  that 
the  absence  of  aphasia,  in  cases  where  the  muscles  of  the  face, 
arm,  or  hand  are  paralyzed,  is  probably  confined  to  lesions 
affecting  only  the  right  side  of  the  cerebrum. 

The  lesions  in  which  aphasia  exists  have  been  considered 
somewhat  at  length  in  previous  pages  of  this  chapter,  but  the 
fact  that  most  of  the  clinical  cases  recorded  have  failed  thus 
far  to  overthrow  the  discovery  of  Broca  *  seems  to  place  it  upon 
a  footing  above  that  of  mere  empirical  generalization.  Cases 
have  been  reported  where  aphasia  has  been  the  result  of  frac- 
ture of  the  left  side  of  the  skull  in  the  region  of  the  frontal 
lobes,'  and  also  where  recovery  of  the  power  of  speech  fol- 

^  Reported  by  Bourdon,  "  Centres  moteurs  des  membres."     Paris,  1877. 

2  Gowers,  article  in  "Brain,*'  1878. 

3  See  the  relation  of  the  facial  centers,  Nos.  7,  8,  11,  to  those  of  the  arm  and  hand, 
Nos.  4,  5,  6,  a,  6,  c,  d,  and  to  the  oro-lingual  centers,  Nos.  9, 10,  in  Fig.  15  of  this  yolumc. 

^  Some  late  observations  apparently  point  to  other  centers,  as  associated  with  speech, 
besides  that  of  Broca.  ^  Mac  Cormac,  "  Brain,"  1877. 


U  THE  BRAIN. 

lowed  the  operation  of  trephining,'  but  it  occurs  most  fre- 
quently as  the  result  of  embolic  obstruction  of  the  middle 
cerebral  artery  or  of  some  of  its  branches." 

Diagnosis  of  Cortical  Motor  Paralysis. — The  effects  of 
lesions  which  involve  the  corpus  striatum  of  either  side,  or 
the  anterior  two  thirds  of  the  internal  capsule  of  the  cere- 
brum, differ  but  little  from  those  of  lesions  which  are  confined 
to  the  motor  area  of  the  cerebral  convolutions,  since  the  fibers 
which  are  affected  in  either  case  are  the  same." 

After  the  effects  of  the  shock  of  the  attack  have  passed 
away,  the  muscles  which  are  paralyzed  are  usually  those 
which  are  the  most  completely  under  the  control  of  voli- 
tion; thus  the  lower  muscles  of  the  face  are  more  affected  than 
those  upon  the  forehead  or  of  the  eyelids,  since  the  lower 
facial  muscles  are  by  far  the  most  voluntary  ;  the  muscles  of 
the  hand  are  very  markedly  affected,  even  more  than  those  of 
the  arm  ;  and  the  muscles  of  the  upper  extremity  more  than 
those  of  the  lower.* 

No  evidence  of  impairment  of  sensation  can  be  discovered, 
provided  that  the  posterior  third  of  the  internal  capsule  of 
the  cerebrum  has  escaped  injury.  The  nutrition  of  the  para- 
lyzed muscles  is  apparently  normal,  and  their  electric  con- 
tractility is  not  impaired. 

A  tendency  toward  rigidity  of  the  paralyzed  muscles  de- 
velops, later  on  in  the  disease,  which  has  been  variously  ex- 
plained by  some  authors  (Charcot,  Bastian,  and  Bouchard)  as 
the  result  of  a  progressive  sclerosis.,  which  descends  along  the 
motor  tract  of  the  pons  Varolii,  crus  cerebri,  medulla,  and 
the  spinal  cord  ;  while  the  researches  of  Hughlings- Jackson ' 

^  Terrillon  and  Proust,  "Acad,  do  Medicine,"  ISYG. 

'  See  researches  of  Meissner,  Charcot,  Vulpian,  Seguin,  Bertin,  and  others. 

*  Ferrier,  op.  cit.  The  reader  is  referred  to  Fig.  8  of  this  volume,  in  explanation  of 
this  statement. 

^  Pathological  anatomy  (recent  cases)  demonstrates:  1,  that  destructive  lesions  of  the 
motor  regions  of  the  cortex  (and  of  the  para-central  lobule)  produce  descending  degenera- 
tion throughout  the  direct  cerebral  motor  tract,  extending  into  the  lateral  columns  of  the 
spinal  cord  ;  and  2,  that  there  is  a  remarkable  correspondence  between  certain  localized 
spasmodic  and  paralytic  symptoms  observed  during  life  and  lesions  irritating  or  destroy- 
ing certain  definite  spots  in  the  motor  zone  of  the  cortex. 

"  "  Medical  Examiner,"  April,  1877. 


I 


TYPES  OF  MONOPLEGIA.  45 


warrants  Mm  in  discarding  this  explanation  and  attributing 
it  to  an  unimpeded  cerebellar  influence.,  whicli  is  no  longer 
controlled  by  the  cerebrum.  Both  of  these  hypotheses  are, 
however,  discarded  by  Buret,'  who  considers  the  rigidity 
to  be  the  result  of  simple  reflex  irritation.  It  will  in  no 
way  add  to  the  practicability  of  the  matter  contained  here 
to  enter  into  the  discussion  of  the  relative  demerits  of  these 
theories,  since  those  interested  in  the  subject  will  find  Ter- 
rier's work  on  the  ''Localization  of  Cerebral  Disease"  and 
many  of  the  advanced  works  upon  the  pathology  of  dis- 
eases of  the  nervous  system  to  contain  all  the  desired  infor- 
mation. 

One  of  the  most  valuable  signs  of  paralysis  dependent  upon 
a  lesion  of  the  cortex  is  the  fact  that  the  condition  is  not  one 
of  complete  hemiplegia,  but  rather  of  monoplegia,  in  which 
special  groups  of  muscles  only  are  deprived  of  voluntary 
motion  :  thus,  the  arm  and  leg  may  be  affected  together  ;  again, 
the  arm,  hand,  and  face  ;  the  arm  alone  ;  the  leg  alone ;  cer- 
tain movements  only  of  either  extremity  ;  and  all  other  possi- 
ble combinations.  Paralysis  due  to  lesions  of  the  cortex  may 
often  be  transitory,  if  the  lesion  be  slight  and  superficial ;  or 
it  may  be  permanent,  if  deep  and  impinging  upon  the  medulla. 
It  is,  furthermore,  frequently  associated  with  rigidity  in  its 
early  stages,  which  is  a  rare  occurrence  in  central  cerebral 
disease. 

In  attacks  of  paralysis  due  to  suddenly  developed  lesions 
of  the  cortex,  consciousness  is  less  frequently  lost  than  in 
similar  lesions  of  the  central  ganglia,  and  pain  of  a  local  char- 
acter within  the  head  is  often  either  complained  of  by  the  pa- 
tient spontaneously  with  the  attack,  or  it  may  be  sometimes 
elicited  by  percussion  over  the  seat  of  the  exciting  lesion. 
The  loss  of  consciousness  which  generally  accompanies  any 
sudden  lesion  of  the  central  ganglia  is  explained  by  Bu- 
ret '  as  due  to  a  rapid  displacement  of  the  cerebrospinal 
fluid,  which  in  turn  creates  a  general  disturbance  of  the  cir- 

^  "Brain,"  Parti,  18VY. 

*  "  Traumatismes  cercbraux,"  Th^se,  1878;  "Archiv.  de  Physiologic,"  ISYS. 


46  THE  BRAIN. 

culation  of  the  cerebrum,  since  this  fluid  serves  to  establish 
a  uniformity  of  pressure  throughout  the  brain. 

Ferrier '  thus  briefly  summarizes  the  results  of  clinical  ob- 
servation bearing  upon  the  diagnosis  of  paralysis  dependent 
upon  destructive  lesions  of  the  cortex:  '^  While  we  can  not 
be  quite  certain  of  the  position  or  extent  of  a  cortical  lesion 
causing  a  sudden  and  complete  hemiplegia,  we  may  take  a 
monoplegia  of  the  leg,  or  of  the  arm  and  leg,  as  an  indication 
of  a  lesion  of  the  upper  extremity  of  the  ascending  convolu- 
tions close  to  the  longitudinal  fissure  ;  brachial  monoplegia, 
as  a  sign  of  a  lesion  in  the  upper  part  of  the  ascending  fron- 
tal convolution,  or,  if  the  paralysis  affect  tlie  hand  more 
particularly,  of  the  ascending  parietal  convolution  ;  hrachio- 
facial  monoplegia,  as  indicating  a  lesion  of  the  mid-fronto- 
parietal  region  ;  while /acm?  and  lingual  monoplegia,  or  this 
combined  with  aphasia,  indicates  a  lesion  of  the  lower  part  of 
the  ascending  frontal  convolution  where  the  third  frontal 
joins  with  it."  '^ 

Irritative  Lesions  of  the  Motor  Area. — It  is  a  well-recog- 
nized fact  in  clinical  experience  that  certain  symptoms,  which 
are  chiefly  of  a  convulsive  type,  are  dependent  upon  conditions 
which  create  simply  irritation  of  certain  portions  of  the  cere- 
brum, without  any  actual  destruction  of  the  gray  or  w^hite 
matter.  Among  the  various  conditions  which  are  esjiecially 
liable  to  produce  such  local  irritation  may  be  mentioned 
syphilitic  meningo-encephalitis,  simple  inflammation  of  the 
same  character,  deposit  of  tubercle,  superflcial  cysts  or  tu- 
mors of  a  more  solid  character,  spiculae  of  bone,  cicatrices 
from  wounds  of  previous  date,  suppuration  from  caries  and 
necrosis,  etc. 

In  the  year  1867,'  and  still  later,  in  the  year  1871,*  the 
general  statement  by  which  the  clinical  diagnosis  of  the  situa- 
tion of  irritative  lesions  of  the  cerebrum  might  be  assisted  was 

'  Op.  cit. 

'  The  plate  showing  the  motor  centers  will  tend  to  explain  these  deductions.     Sec 
page  39  of  this  volume. 

3  "  St.  Bartholomew's  Hospital  Reports." 
*  "  Medico-Chir.  Trans." 


JACKSOmAN  EPILEPSY.  4Y 

advanced  by  Callender,  "that  convulsive  attacks  were  most 
commonly  associated  with  superficial  lesions  of  the  cortex  sit- 
uated in  the  immediate  vicinity  of  the  middle  meningeal  ar- 
tery." Ferrier,  however,  concludes,  as  the  result  of  his  exten- 
sive facilities  for  observation,  that,  while  this  may  be  useful  as 
a  general  rule,  still  any  portion  of  the  cortex  of  the  hemi- 
sphere may  result  in  convulsions  of  the  opposite  side  of  the 
body,  and  he  adds  the  statement  that  the  seat  of  an  irritative 
lesion  can  be  less  accurately  determined  than  one  of  a  destruc- 
tive character,  owing  to  the  difficulty  of  determining  the  ex- 
tent of  the  zone  in  which  vital  irritation  concentrates  itself. 

Hughlings- Jackson '  has  contributed  much  to  the  pathology 
of  those  conditions  of  the  cortex,  produced  by  irritation,  which 
manifest  themselves  in  the  form  of  convulsions.  So  great  a 
prominence  did  syphilis  have  as  one  of  the  exciting  causes  of 
such  irritation  that  the  term  ''Jacksonian  epilepsy  "  is  now 
often  used  as  synonymous  with  the  convulsions  met  with  in 
that  disease.  The  theory  which  this  author  advances  to  ex- 
plain these  convulsive  attacks  is  as  follows  :  That  irritation 
of  the  cortex  tends  toward  an  abnormal  accumulation  of  ner- 
vous energy,  so  that  the  aft'ected  part  is  under  a  state  of  high 
tension,  and,  under  certain  conditions,  this  irritated  portion 
discharges  itself  in  a  sudden  and  explosive  manner,  thus  pro- 
ducing a  subsequent  exhaustion  of  its  powers ;  hence  a  con- 
vulsion, and  often  some  type  of  monoplegia  following  it. 

The  convulsions  dependent  upon  irritation  of  the  cortex 
may  assume  all  of  the  diiferent  varieties  produced  by  de- 
structive lesions  of  the  motor  area,  and  may  even  result  in 
paralysis  ;  thus  the  leg  may  alone  be  affected  with  spasm, 
the  arm  alone,  the  arm  and  hand  together,  and  the  face  alone, 
or  in  connection  with  the  upper  extremity. 

It  may  often  assist  in  the  localization  of  a  lesion,  which  is 
creating  the  irritation  of  the  cortex,  to  note  carefully  the  mus- 
cles affected  at  the  onset  of  the  convulsion,  since  they  may 
enable  the  observer,  through  a  knowledge  of  the  motor  cen- 
ters, to  trace  the  seat  of  the  region  within  the  cortex  which 

^  Oj).  cit.     Also  see  "Medical  Times  and  Gazette,"  ISVS. 


48  THE  BRAIN. 

first  exhibited  a  tendency  to  explosive  discharge  of  its  nerv- 
ous energy. 

THE  SENSORY  REGIONS  OF  THE  CEREBRUM. 

The  temporo-sphenoidal  and  occipital  lobes  of  the  cerebrum 
are  now  accepted  by  most  authors  as  the  only  portions  which 
can  appreciate  the  perception  of  sensory  impressions.  This 
fact  seems  to  be  demonstrated  not  only  by  experimental  in- 
vestigation upon  animals,  but  also  by  clinical  observation, 
with  as  great  a  degree  of  certainty  as  previous  facts  which 
have  been  mentioned  regarding  the  function  of  the  frontal 
region  and  the  motor  area. 

It  has  been  determined,  with  some  approach  to  positive- 
ness  of  statement,  that  the  posterior  fibers  of  the  cms  are 
the  principal  means  of  transmission  of  sensory  impressions 
from  the  periphery  of  the  body  to  the  cerebrum,  and  the 
researches  of  Meynert  have  done  much  to  demonstrate  that 
these  fibers  are  connected  with  the  portions  of  the  cortex 
which  have  been  designated  as  the  regions  chiefly  associated 
with  sensory  perception. 

Duret,'  Veyssiere,"  and  Raymond  have  shown  by  experi- 
ment that,  when  that  part  of  the  internal  capsule  which  is 
situated  between  the  lenticular  nucleus  and  the  optic  thala- 
mus is  divided,  a  loss  of  sensation  is  experienced  in  the  oppo- 
site side  of  the  body,  but  that,  in  some  instances,  some  degree 
of  motor  paralysis  is  also  produced.  On  the  other  hand, 
these  same  observers  have  found  that  section  of  the  anterior 
two  thirds  of  the  internal  capsule  produces  a  distinct  motor 
paralysis,  with  no  effect  upon  the  function  of  sensory  percep- 
tion of  the  parts  paralyzed,  save  in  a  few  instances,  where 
such  a  result  of  a  fleeting  character  was  detected. 

That  these  deductions  are  fully  sustained  by  clinical  facts, 
as  fnr  as  the  motor  nerves  are  concerned,  the  statements  of 
preceding  pages  seem  to  clearly  prove,  and  the  collected  cases 

'  Op.  tit. 

3  "  Sur  rh6mianesth6sie  de  cause  c6r6brale,"  1874. 


THE  OCCIPITAL  LOBES.  49 

reported  by  Charcot/  Pitres,'  Turck/  and  others,  present  a 
large  mass  of  evidence  to  warrant  the  conclusion  that  lesions 
of  the  posterior  part  of  the  internal  capsule  are  indicated  by 
hemi-ansesthesia  on  the  side  of  the  body  opposite  to  the 
lesion.  In  such  cases,  tactile  sensation  is  destroyed  to  the 
median  line  not  only  in  the  trunk,  but  also  upon  the  face ; 
pain  and  the  sensation  of  heat  are  likewise  abolished  ;  but  the 
contractility  of  muscles  under  the  electric  current  is  not  im- 
paired or  lost.  If  we  examine  the  mucous  membranes  of  the 
eye,  nose,  or  mouth,  the  same  condition  of  destroyed  sensi- 
bility will  be  detected,  but  the  viscera  remain  sensitive. 
Furthermore,  taste,  smell,  and  hearing  are  usually  rendered 
deficient,  and,  in  some  cases,  are  entirely  abolished,  on  the 
side  opposite  to  the  lesion ;  and  the  special  sense  of  sight  is 
affected  in  a  variety  of  ways,  which  will  be  described  in 
detail. 

In  the  admirable  work  of  Charcot,  *  a  diagram  is  given  to 
ustrate  the  effect  of  pressure  upon  the  optic  tract,  the  com- 
issure,  and  the  optic  nerve  itself,  which  I  shall  use  in  the 
scussion  of  the  value  of  the  optic  nerve  as  a  guide  in  diag- 
osis  later  in  this  course  ; '  but  the  clinical  facts  afforded  by 
sions  within  the  internal  capsule  fail  to  support  similar  re- 
ults  as  the  effect  of  intra-cerebral  pressure.     Thus,  in  lesions 

if  the  internal  capsule,  blindness  of  the  lateral  half  of  both 
etinse  (?iemianopsia\  as  one  would  expect  to  find,  does  not 
xist ;  but,  on  the  contrary,  a  condition  of  amblyopia  results, 
rhich  is  characterized  by  a  marked  contraction  of  the  field 
•f  vision,  and  especially  so  as  regards  the  perception  of  color. 
By  consulting  the  diagram  given  you  in  the  description  of 
bhe  optic  nerve,"  you  will  perceive  that  the  field  for  blue  tints 
K  the  largest,  and  that  red  is  next  in  point  of  size,  while 

f       1  "  Lccons  sur  les  maladies  du  systeme  nerveux." 
f        2  "  Lesions  du  Centre  Ovale." 

2  See  Grasset,  "Localizations  dans  les  maladies  cerebrales,"  1S78. 

4  Op.  cit. 

5  The  reader  is  referred  to  the  diagrammatic  cut  and  its  descriptive  text  in  the  lecture 
on  the  optic  nerve. 

6  See  page  of  this  volume  containing  a  diagram  by  Hirschberg. 


50  TEE  BRAIN. 

green  comes  last.'  Now,  in  lesions  of  the  internal  capsule, 
the  perception  of  these  colors  is  impaired  in  the  relative  pro- 
portion of  the  size  of  the  field,  and  thus  green  may  be  en- 
tirely lost,  while  the  vision  of  red  or  blue  may  still  remain. 

It  has  been  shown  by  Landolt,''  who  has  done  much  to 
develop  this  special  field  of  investigation,  that  the  impairment 
of  vision  from  intra-cerebral  causes  is  not  altogether  confined 
to  one  side,  but  that  the  eye  upon  the  same  side  as  the  lesion 
is  somewhat  affected,  and  rendered  partially  anaesthetic. 

If  we  examine  the  eyes  so  affected,  we  can  not  discover 
by  the  ophthalmoscope  any  organic  disease  or  evidences  of 
degeneration  of  either  the  optic  nerve  or  the  retina,  provided 
that  the  examination  is  made  early,  before  any  late  results  of 
the  blind  condition  of  the  eye  manifest  themselves  as  the 
effect  of  disuse." 

As  has  been  before  stated,  the  condition  of  amblyopia  and 
the  absence  of  hemianopsia  are  in  opposition  to  what  the  ef- 
fects of  pressure  upon  the  optic  tracts  would  seem  to  suggest, 
but  we  still  have  a  clinical  fact  to  explain,  viz.,  that  hemi- 
anopsia does  sometimes  occur  with  attacks  of  hemiplegia. 
Ferrier  states  positively  that,  in  such  cases  as  these,  we  may 
conclude  that  the  lesion  must  be  either  situated  below  the 
cerebral  cortex,  or  exert  its  influence  below  the  cortex,  in 
case  it  be  contained  within  it.  The  angular  gyrus,*  which  is 
now  considered  as  the  probable  center  of  vision,  does  not 
seem  to  exert  any  influence  upon  the  motor  apparatus,  as  is 
shown  by  its  destruction  in  animals. 

The  Occipital  Lobes  of  the  cerebrum  have  been  stated  to 
be  properly  included  among  the  sensory  regions  of  the  cortex. 
Experiments  of  section,  or  even  of  complete  removal  of  these 
lobes  of  one  or  both  sides,  however,  fail  to  show  any  effect 


'  Violet  has  a  still  smaller  field,  but  it  is  not  shown  upon  the  chart. 

2  "  La  France  Medicalc,"  1877. 

3  Any  inter-cranial  lesion  which  acts  in  such  a  way  as  to  increase  the  mtra-cranial 
presmre  may  produce  (in  addition  to  other  symptoms)  the  condition  known  as  "  choked 
disk,"  or  a  neuro-rctinitis. 

^  The  reader  is  referred  to  the  lecture  on  the  optic  nerve  for  further  information  upon 
this  point. 


THE  OCCIPITAL  LOBES.  51 

upon  sensory  or  motor  functions.  So  negative,  indeed,  arc 
these  results  that  no  disturbance  of  taste,  hearing,  touch, 
smell,  or  sight '  has  been  positively  produced.  It  is  from  the 
absence  of  positive  experimental  deduction  as  to  these  lobes 
that  the  distribution  of  the  decussating  fibers  of  the  optic 
tracts  to  the  occipital  lobes  may  be  yet  considered  as  ques- 
tionable, although  such  an  anatomical  distribution  is  stated, 
by  many  late  authors,  "^  to  be  capable  of  verification. 

Certain  clinical  facts,  however,  seem  to  warrant  the  belief 
that  the  occipital  lobes  are  associated  with  more  apparent 
mental  derangement  than  the  frontal  or  temporo-sphenoidal 
lobes,  in  case  they  be  the  seat  of  disease,  and  the  conclusion 
of  FerrierMs  thus  stated,  as  an  hypothesis:  " The  occipital 
lobes  are  specially  related  to  the  visceral  sensibilities,  and  are 
the  anatomical  sub- strata  of  the  correlative  feelings  which 
form  a  large  portion  of  our  personality  and  subjectivity."  It 
is  claimed  by  Hughlings- Jackson  that  irritative  lesions  of  the 
cipital  lobes  give  rise  to  colored  perception  of  objects  and 
ther  ocular  spectra,  and  he  further  states  that  such  evidences 
of  defective  perception  are  more  common  when  the  lesion 
affects  the  right  side. 

The  Temporo-spheis^oidal  Lobes  are  situated  between  the 
motor  area,  in  front,  and  the  occipital  lobe,  behind.  The  fol- 
lowing deductions  have  been  drawn,  by  experimental  re- 
search, as  to  the  special  functions  of  this  lobe  and  some  of 
the  adjoining  convolutions,  which  will  require  separate  con- 
sideration : 

The  apparent  connection  of  this  region  with  the  special 
sense  of  mslon  has  been  noticed  by  Hitzig,  Goltz,  and  McKen- 
drick,  the  two  former  of  whom  confined  their  experiments  to 
the  dog  species,  while  the  latter  operated  exclusively  upon 
pigeons.  Ferrier,'  however,  from  a  belief  that  other  functions 
could  be  demonstrated  as  pertaining  to  this  locality,  and  from 

^  Munk  claims  to  have  positively  proved  an  association  of  the  occipital  lobe  with  vis- 
ion, but  his  experiments  have  not,  as  yet,  been  fully  substantiated. 
^  Researches  of  Fcrrier,  Yeo,  Dalton,  and  others. 
^  "  Localization  of  Cerebral  Disease." 
*  Op.  cit.  ;  Terrier  and  Yeo,  "Brain,"  1880  ;  Exner,  "Brain,"  October,  1880. 


Foti 


52  THE  BBAIK 

disbelief  in  the  method  pursued  by  Goltz/  as  adapted  to  the 
requirements  of  experimental  research  concerning  the  func- 
tions of  limited  areas  of  the  cortex,  made  a  series  of  experi- 
ments upon  the  brains  of  monkeys,  and  claims  to  have  estab- 
lished some  new  points  of  physiological  interest,  and,  possibly, 
of  practical  value  in  cerebral  localization. 

The  conclusions  which  were  drawn  as  the  results  of  the 
labors  of  this  learned  and  original  investigator  may  be  thus 
summarized : 

1.  In  the  angular  gyrus  ^  is  situated  a  center,  which 
causes,  on  electric  irritation,  certain  movements  of  the  eyes, 
pupils,  and  head,  but  whose  destruction  creates  no  evidence 
of  motor  paralysis  in  the  muscles  of  either  the  eye,  its  lids,  or 
the  pupil.  Unilateral  destruction,  however,  of  this  center 
causes  blindness  of  the  opposite  eye,  which  proves  but  tem- 
porary ;  while  the  destruction  of  doth  sides  causes  a  perma- 
nent loss  of  sight  in  both  eyes."  It  thus  appears  that  the 
center  of  either  side  is,  to  some  extent,  connected  with  both 
eyes. 

2.  In  the  superior  temporo- sphenoidal  convolution*  is 
found  to  exist  a  center  which,  under  galvanic  stimulation, 
creates  a  twitching  of  the  opposite  ear  and  a  modification  in 
hearing  of  the  opposite  side,  but  which  it  was  found  difficult 
to  fully  ascertain  on  account  of  the  animal  not  being  able  to 
exhibit  appreciation  of  modification  of  that  special  sense.  As 
in  the  preceding  center,  destruction  of  this  convolution,  upon 
one  side,  caused  some  abnormality  of  hearing ;  and,  when 
both  sides  were  destroyed,  the  animal  became  totally  deaf, 
but  no  motor  paralysis  could  be  discovered  in  either  case. 

3.  In  the  lower  extremity  of  the  lobe  previously  desig- 
nated, a  center  was  found  which  seemed  to  exert  an  influence 
upon  the  special  sense  of  smell,  and  also  motions  of  the  nos- 

•  That  of  trcphininj*  over  the  spot  selected  for  investigation,  and  washing  away  the 
brain  by  a  forcible  stream  of  water. 

■''  Regions  marked  lo  in  Fig.  15  of  this  volume. 

'  The  experiments  of  Munk,  Luciani,  Tamburini,  Ferrier,  Yco,  Dalton,  and  others,  upon 
these  centers  leave  the  field,  as  yet,  a  matter  for  further  investigation. 

*  Sec  diagrammatic  cut  on  page  39  of  this  volume;  regions  marked  14. 


THE  TEMPOEO'SPHENOIDAL  LOBES. 


53 


tril  and  head  wMcli  indicated  excitation  of  that  sense.  In 
the  regions  adjacent  to  this  convohition  the  special  sense  of 
taste  became  affected  when  destroyed  ;  and,  when  the  convo- 
lution and  the  adjacent  region  were  destroyed,  upon  both 
sides,  taste  and  smell  were  utterly  lost.  In  regard  also  to 
these  two  centers,  unilateral  destruction  created  the  most 
marked  effects  upon  the  side  opposite  to  the  lesion,  while 
a  bilateral  destruction  abolished  the  sense  altogether. 

4.  In  the  region  of  the  Mppocampus  some  evidence  was 
given  of  the  control  over  tactile  sensation^  but  the  situation 


Fig.  17. — A  diagram  illustrating  tlie  c^yiirf^e  of  nerve  impulses  in  the  ecrebrum.  (After  Dodds.) 

A,  the  motor  regions  of  the  cerebral  cortex,  represented  by  arrow-heads ;  B,  the  sensor^/ 
regions  of  the  cerebral  cortex,  represented  by  circles ;  C,  commissural  fibers,  con- 
necting the  two  regions  of  the  cortex  (probable,  but  not  positively  demonstrated); 

D,  sensory  nerve  fibers^  the  arrow  showing  the  centripetal  direction  of  the  impulse ; 

E,  mok>r  7ierve  fibers,  the  arrow  showing  the  centrifugal  direction  of  the  impulse ; 
C.  S,  "  corpus  striatum  "  (the  probable  motor  ganglion  at  the  base  of  the  cerebrum) ; 

0.  T,  "  optic  thalamus  "  (the  probable  sensory  ganglion  at  the  base  of  the  cerebrum) ; 

1,  a  few  sensory  fibers,  possibly  connected  with  the  "corpus  striatum";  2,  a  few 
motor  fibers,  possilily  connected  with  the  "  optic  thalamus." 


of  the  part  rendered  experiment  upon  it  difficult,  and  some- 
what less  positive  than  those  upon  the  areas  previously  dis- 
1=  cussed.        a 


54  THE  BRAIN. 

It  is  to  be  regretted  that  the  conclusions  of  this  author  as 
to  the  situation  of  these  special  centers  in  the  sensory  regions 
of  the  cerebrum  should  not  be  as  positively  sustained  by  clin- 
ical and  pathological  facts  as  were  the  conclusions  drawn 
from  experimental  research  upon  the  motor  area  of  the  brain 
of  the  monkey  tribe.  Ferrier  endeavors  to  explain  the  dis- 
crepancy between  the  facts  obtained  by  experiment  and  those 
afforded  by  disease  of  the  same  regions  in  the  human  brain, 
by  the  hypothesis  that  the  special  senses  may  be  governed 
by  a  bilateral  rather  than  a  unilateral  impulse,  as  the  ex- 
perimental facts  pertaining  to  the  special  senses  of  sight  and 
hearing  seem  to  warrant,  and  this  has  not,  as  yet,  been  dis- 
proved, since  all  of  the  cases  recorded  have  been  of  a  uni- 
lateral character. 

To  what  extent  these  physiological  subdivisions  of  the 
sensory  area  of  the  cerebrum  may  be  regarded  as  of  prac- 
tical utility  in  diagnosis  can  hardly  be  determined,  as  the 
field  is  still  a  new  one,  and  the  collection  of  clinical  and 
pathological  records  is  insufficient  for  a  basis  of  positive  de- 
duction. 


THE   CORPUS   STRIATUM  AND  OPTIC  THALAMUS. 

These  two  bodies,  which  are  called  the  "basal  ganglia" 
of  each  cerebral  hemisphere,  are  undoubtedly  a  means  of 
communication  between  the  gray  matter  of  the  convolutions 
and  the  fibers  of  the  crura  cerebri.  While  it  can  not  be  de- 
nied that  some  of  the  fibers  of  the^  internal  capsule  are  in  no 
way  connected  with  these  ganglia,  and  that  a  portion  of  the 
fibers  which  pass  through  them  on  the  way  to  the  convolu- 
tions are  apparently  independent  of  the  nerve  cells  of  these 
ganglia,  still  the  gi-eater  proportion  of  the  peduncular  fibers 
of  the  cerebrum  are  undoubtedly  indirectly  connected  with 
the  gray  matter  of  the  convolutions,  being  intimately  asso- 
ciated with  the  nerve  cells  of  wl;ichever  of  the  basal  ganglia 
they  are  obliged  to  pass  through,  in  order  to  reach  the  ex- 
terior portions  of  the  hemispheres. 


t 


TEE  BASAL   GANGLIA. 


55 


It  is  tlius  afRrmed,  by  many  of  our  later  physiologists,  that 
these  ganglia  act  in  the  capacity  of  middle-men  between  the 
gray  matter  of  the  convolutions  and  the  rest  of  the  component 
parts  of  the  brain,  and  that  they  exercise  an  important  influ- 
ence in  mediating  between  the  psychical  operations  of  the  cor- 
tex and  the  moto-sensory  functions  of  the  remaining  parts. 


Fig.  18. —  Corpora  striata.  (Sappey.) 
1,  fifth  ventricle ;  2,  the  two  lamina)  of  the  septum  lucidum  meeting  in  front  of  the  fifth 
ventricle ;  3,  hippocampus  minor ;  4,  posterior  portion  of  the  corpus  callosum ;  5, 
middle  portion  of  the  fornix ;  6,  posterior  pillar  of  the  fornix ;  Y,  hippocampus  major ; 
8,  cminentia  collateralis ;  9,  lateral  portions  of  the  fornix;  10,  choroid  plexus;  11, 
taenia  semicircularis ;   12.  corpus  striatum. 

From  the  statement  in  previous  lectures  of  the  experimen- 
tal and  clinical  deductions  as  to  the  various  portions  of  the 
cortex,  we  may  be  able  now  to  use  with  profit  the  two  axioms 
which  Foster, '  in  his  work  upon  physiology,  lays  down  as  to 
the  general  plan  of  action  of  the  brain  in  all  its  different  parts. 
Thus,  he  says;  ''The  preceding  discussions  enable  us  to  lay 
down  two  broad  propositions  : 

^  Mich.  Foster,  "A  Text-Book  of  Physiology."     London,  1878. 


56  THE  BRAIN. 

"1.  The  functions  of  tlie  cerebral  convolutions  are  emi- 
nently psycliicalm  nature  ;  these  parts  intervene  onl^^in  those 
operations  of  the  nervous  system  in  which  an  intelligent  con- 
sciousness and  volition  play  a  part. 

"2.  The  hinder  parts  of  the  brain,  viz.,  the  corpora  quad- 
rigemina,  crura  cerebri,  pons  Varolii,  cerebellum,  and  medulla 
oblongata,  are  capable  by  themselves  of  carrying  into  execu- 
tion complex  movements^  the  coordination  of  which  implies 
very  considerable  elaboration  of  afferent  impulses  ;  and  they 
can,  in  the  case  of  animals,  even  do  this  with  the  total  ab- 
sence of  the  cerebral  hemispheres,  corpora  striata,  and  optic 
thalami." 

The  hypothesis,  which  was  long  since  advanced  by  Car- 
penter* and  also  by  Todd,"  that  the  corpus  striatum  is 
called  into  action  in  the  downward  transmission  of  motor 
impulses  to  the  opposite  side  of  the  body,  and  that  the 
optic  thalamus  was  the  center  of  elaboration  and  transmission 
upward  of  sensory  impressions^  seems  to  be  accepted  as 
proven  by  some  authors,  while  others  are  inclined  to  regard 
it,  in  the  light  of  imperfect  evidence,  as  a  pleasing  but  specu- 
lative theory.  The  distribution  of  the  fibers  of  the  crus 
cerebri  certainly  points  strongly  to  the  corpus  striatum  as  a 
motor  ganglion,  and  to  the  optic  thalamus  as  one  destined  to 
preside  over  sensory  impulses. 

The  results  of  experimental  investigation  as  to  the  corpora 
striata '  can  hardly  be  said  to  warrant  any  positive  deductions. 
In  some  instances,  the  entire  removal  of  these  ganglia  resulted 
in  no  loss  of  either  sensation  or  motion,  although  it  is  a  well- 
recognized  clinical  fact  that  haemorrhage  into  this  ganglion 
causes  hemiplegia  of  the  opposite  side.*  It  would  seem  also 
that  convulsions  are  more  frequently  produced  by  lesions  con- 
fined to  the  corpora  striata  than  when  affecting  the  oi^tic  tha- 

'  W.  B.  CarpenttM-,  "  Principles  of  Human  Physiology." 

'  Todd  and  Bowman,  "  Physiological  Anatomy." 

3  The  corpus  striatum  of  each  hemisphere  tiUicn  collectively ;  hence  the  plural  termi- 
nation. 

*  Probably  the  pressure  created  upon  the  anterior  part  of  the  internal  capsule  cxplaina 
these  phenomena.     (See  Fig.  8.) 


TEE  BASAL   GANGLIA,  57 

lami,  and  these  convulsive  movements  are  generally  crossed, 
like  the  paralysis  of  motion,  in  case  of  haemorrhage.  Both  Fer- 
rier '  and  Burdon- Sanderson '  found  that  galvanic  stimulation 
of  the  corpus  striatum  could  be  made  to  produce  convulsive 
movements,  and  occasionally  a  condition  of  complete  pleuros- 
thotonos  of  the  opposite  side. 

The  two  portions  of  the  corpus  striatum  which  are  now 
recognized,  viz.,  the  ventricular  portion'  and  the  lenticular 
nucleus,  have  both  been  the  subject  of  special  investigation 
by  Nothnagel ;  *  but,  while  neither  seemed  to  be  concerned  in 
the  perception  of  sensory  impressions,  nothing  of  a  positive 
character  as  regards  the  functions  of  the  two  portions  was 
proven,  although  the  ventricular  portion  seemed  to  show  less 
effect  upon  voluntary  motion  than  the  lenticular  nucleus, 
when  both  sides  were  destroyed. 

The  optic  thalami  were  once  supposed  to  be  the  chief  gan- 
glia of  vision,  but  that  this  is  an  error  investigation  seems  to 
have  partly  proven.  Longet'  has  succeeded  in  destroying 
them  upon  the  two  sides,  and  has  been  unable  to  note  any 
impairment  in  vision  or  influence  upon  the  movements  of  the 
pupil ;  but  Lusanna  and  Lemoigne '  state  that  blindness  of 
the  opposite  eye  followed  destruction  of  the  ganglion  upon 
one  side  only. 

Cases  of  cerebral  haemorrhage  throw  but  little  light  upon 
the  function  of  these  ganglia,  since  the  destruction  of  brain 
tissue  is  seldom,  if  ever,  confined  to  these  ganglia  only,  and, 
in  those  cases  where  its  limits  were  nearly  confined  to  this 
region,  paralysis  of  sensation  of  the  opposite  half  of  the  body 
has  been  noticed  without  actual  loss  of  motion  upon  that 
side,  although  the  movements  may  have  been  somewhat  en- 
feebled.' 


^  "Functions  of  the  Brain,"  New  York,  1879. 
2  "Proc.  Roy.  Soc.,"  1875. 


^  Another  name  for  the  "  caudate  nucleus  "  of  the  corpus  striatum. 

*  Virchow's  "  Arehiv,"  1873.     This  observer  used  injections  of  chromic  acid  into  the 
lenticular  nucleus,  and  destroyed  the  caudate  nucleus  by  means  of  a  special  instrument. 

*  "  Traite  de  Physiologic." 

«  "Fistologia  die  Centri  Nervosi  Encefalici,"  1871. 
'  Brown-Sequard,  "Arehiv.  de  Physiol,"  1877. 


58  I^E  BRAIN. 


THE  CORPORA  QUADRIGEMINA. 

The  experiments  of  Adamiik, '  by  whicli  he  endeavored  to 
prove  the  existence  of  a  center  or  a  collection  of  centers  in  the 
nates,  whose  function  was  to  control  the  movements  of  the 
eyeball,  will  be  considered  in  connection  with  the  motor  ocnli 
nerve.'  They  seem  to  be  substantiated  in  great  measure  by 
Hensen,  Yoelkers,  and  Knoll ;  and  that  a  center  also  exists 
in  the  nates  which  contracts  the  pupil  is  quite  as  positively 
ascertained.  This  arrangement  is  in  accordance  with  the  wise 
provisions  of  nature,  since  the  movements  of  the  eyeball  and 
the  pupil  (which  are  constantly  associated)  are  thus  controlled 
by  centers  in  close  proximity  to  each  other. 

The  experiments  of  Hensen,'  and  also  of  Voelkers,*  seem 
to  point  to  the  aqueduct  of  Sylvius,  which  lies  immedi- 
ately underneath  the  tubercula  quadrigemina,  as  the  exact 
seat  of  these  centers,  since  stimulation  of  the  deep  por- 
tions of  the  nates  after  section  produces  more  uniform  re- 
sults than  could  be  obtained  before  the  deeper  parts  were 
exposed. 

Destruction  of  either  side,  in  the  region  of  these  ganglia, 
produces  blindness  of  the  opposite  eye ;  but  the  animal  can 
see,  even  after  the  cerebral  hemispheres  have  been  removed, 
in  case  the  tubercula  quadrigemina  are  left  intact.  This  latter 
statement  seems  somewhat  at  variance  with  the  results  of 
experiments  of  Ferrier  upon  the  angular  gyrus,  as  given  in 
a  previous  lecture  of  this  course,  in  which  vision  was  utterly 
lost  when  both  sides  were  destroyed  ;  but  it  only  goes  to  show 
that  the  cerebral  hemispheres  are  in  some  way  connected  with 
the  tubercula  quadrigemina  in  the  perceptions  gained  by 
sight,  since,  when  the  helnispheres  are  removed,  an  apparently 
crude  vision  remains. 

The  sense  of  sight  has  a  marked  effect  upon  the  coordina- 

^  "  Cbl.  mcd.  Wisa.,"  1870. 
^  Sec  later  pages  of  this  volume. 
3  «'  Archiv.  f.  Ophthalmol.,"  1878. 
*  Ihid.,  1878. 


p 


THE  CENTER  FOR   OCULAR  MOVEMENTS.  59 

tion  of  movement/  and  the  discovery  of  Flourens/  that  the 
removal  of  the  tubercula  quadrigemina  created  impairment  of 
this  power,  sustains  the  belief  that  the  ganglion  of  vision 
must  be  in  some  way  associated  either  with  the  cerebellum, 
crura,  or  pons  Varolii,  in  their  effects  upon  coordination  of 
muscular  movements. 


I 


THE   CRURA  CEREBRI  AND  PONS  VAROLII. 


These  parts  form  the  larger  portion  of  the  meso-cephalon, 
and  are  abundantly  supplied  with  gray  matter,  which  seems 
to  be  mixed  throughout  its  interior.  We  thus  infer  that  these 
parts  have  some  individual  functions,  in  addition  to  being 
simply  connecting  commissures  between  the  upper  parts  of 
the  brain  and  spinal  cord,  but  what  these  functions  are  it  is 
difficult,  at  present,  to  say.  Both  of  these  regions  are  unques- 
tionably connected  in  some  way  with  the  power  of  coordina- 
tion of  muscular  movement,  since  section  of  either  of  them 
! Insults  in  marked  disorder  of  this  function,  and  often  in  un- 
■atural  and  forced  movements. 
I  The  fact  that  some  of  the  nerve  fibers  decussate  in  these 
fcgions  seems  proven  by  clinical  evidence,  since  lesions  of  the 
pons  Varolii  often  ^Todiuo^e.  paralysis  of  the  facial  nerve  upon 
the  same  side  as  the  lesion,  while  the  opposite  side  of  the  body 
■  affected  below  the  face.' 
I  The  facial  nerve  makes  its  exit  from  the  side  of  the  me- 
RuUa  oblongata  ;  some  of  its  roots  of  origin  can  be  traced  as  far 
as  the  floor  of  the  fourth  ventricle,  others  come  from  the  lower 
part  of  the  medulla  oblongata,  and  others  descend  from  the 

^  This  subject  is  quite  fully  discussed  in  connection  with  the  optic  nerve. 

'  "  Recherches  experimentales  sur  les  proprietes  ct  les  fonctions  du  syst^me  nerveux," 
15. 

^  This  class  of  paralysis,  where  certain  cranial  nerves  are  paralyzed  on  the  same  side 

the  existing  lesion,  while  the  body  is  rendered  hemiplegic  on  the  opposite  side,  is 
Q2X\q^ '■'' crossed  paralysis''''  (the  "  paralysie  alterne  "  of  the  French).  It  presents  sfwr«^ 
types  depending  upon  the  cranial  nerve  affected  ;  hence  the  so-called  third  nerve  (motor 
oculi)  and  body  type,  the  fifth  nerve  (trigeminus)  and  body  type,  the  seventh  nerve  (facial) 
and  body  type.  Professor  Romberg  of  Berlin  and  Gubler  of  Paris  have  done  much  to 
elucidate  the  clear  appreciation  of  this  complex  form  of  paralysis  and  the  mechanism  of 
its  production. 


60 


THE  BRAIK 


upper  border  of  the  pons  Varolii,  where  they  probably  decus- 
sate. Now,  a  lesion  existing  in  a  lateral  half  of  the  pons  Va- 
rolii will,  therefore,  produce  a  paralysis  of  the  corresponding 
facial  nerve  and  of  the  opposite  spinal  nerves  ;  whereas,  if  it 
occur  above  the  point  of  decussation  of  the  encephalic  libers, 
the  paralysis  will  be  on  the  opposite  side  for  all  parts  of  the 

body.  These  facts  are  shown 
in  the  accompanying  diagram 
(Fig.  19). 

It  is  obvious,  from  a  study 
of  this  diagram,  that  a  lesion 
of  one  lateral  half  of  the  pons 
(at  l)  will  cause  paralysis  of 
motion  and  of  sensibility  of 
the  opposite  side  of  the  body 
generally,  and  of  the  corre- 
sponding side  of  the  face; 
and  that  a  lesion  of  the  hemi- 
sphere (at  m)  will  produce  pa- 
ralysis of  the  opposite  side  of 
the  face  and  body. 

As  we  might  naturally  ex- 
pect from  the  direction  of  the 
fibers  of  the  pons  Varolii, 
this  portion  of  the  brain  acts 
as  a  direct  conductor  of  both 
motor  and  sensory  impressions 
from  and  to  the  cerebrum ; 
while  the  collections  of  gray 
matter  within  its  substance 
prove  it  to  possess  some  func- 
tions of  its  own  which  are 
independent  of  the  stimula- 
tion of  the  cerebral  cortex. 
Without  entering  into  the  different  experiments  which  have 
been  made  to  determine  the  exact  part  which  this  portion 


Fig.  19. — A  diagram  to  illustrate  the  method 
of  production  of  crossed  paralysis.  (After 
Hammond).' 

rt,  the  left  hemisphere ;  6,  right  half  of  pons ; 
c,  right  half  of  medulla  oblongata ;  f/, 
right  half  of  spinal  cord  ;  c,  right  facial 
nerve ;  /,  fiber  of  origin  from  nucleus 
in  medulla  oblongata;  </,  descending 
fiber  decussating  at  upper  border  of 
pons ;  /i,  ascending  fiber ;  i,  sensory 
root  of  spinal  nerve ;  Ar,  motor  root  of 
sensory  nerve;  /,  lesion  in  pons;  m, 
lesion  in  left  hemisphere ;  w,  paralyzed 
part  supplied  by  facial  nerve  ;  o,  para- 
lyzed part  supplied  by  spinal  nerve. 


'  Hammond,  "  Diseases  of  the  Xervous  System."    New  York,  1876. 


I 


TEE  PONS   VAROLII. 


61 


of  the  meso-cephalon  plays  in  the  complex  machinery  of 
movement  and  sensation,  it  seems  probable  that  the  pons 
Varolii  is  capable  of  originating  a  stimulus  which  may  give 
rise  to  voluntary  motion  without  the  aid  of  the  hemispheres, 
and  that  it  probably  regulates  those  automatic  movements 
which  govern  station  and  progression.  The  experiments  of 
ulpian '  and  Longet '  also  seem  to  prove  that  the  sensation  of 
in  is  perceived  by  the  pons  Varolii  even  when  the  cerebrum 
and  the  basal  ganglia  are  removed,  which,  when  these  por- 
tions are  allowed  to  remain,  are  probably  transmitted  to  the 
hemispheres  as  sensations,  and  are  there  remembered. 


i: 


THE  CEREBELLUM. 

There  seems  to  be  a  greater  contradiction  between  the  de- 
ductions drawn  from  the  results  of  experiment  upon  the  cere- 


FiG.  20. —  Cerehellum  and  medulla  oblongata.     (Hirschfeld.) 
Ij  1,  corpus  dentatum  ;  2,  tuber  annulare  ;  3,  section  of  the  middle  peduncle  ;  4,  4,  4,  4, 
4,  laminae  forming  the  arbor  vitae  ;  5,  5,  olivary  body  of  the  medulla  oblongata ;  6, 
anterior  pyramid  of  the  medulla  oblongata ;  V,  upper  extremity  of  the  spinal  cord. 


bellum  and  the  statistics  of  well-reported  pathological  ob- 
servation than  exists  with  any  of  the  other  ganglia  of  the 


Op.  cit. 


Op.  cit. 


62  THE  BRAIK 

encephalon,  since,  although  the  power  of  governing  coordina- 
tion of  muscular  movements  has  generally  been  attributed  to 
it  by  most  physiologists,  cases  are  on  record  where  the  whole 
ganglion  has  been  almost  destroyed  by  disease  in  man,  and 
still  no  marked  effect  upon  coordination  has  been  observed. 

The  experiments  of  Flourens,'  Bouillaud,''  Yulpian/  and 
others  seem,  however,  to  show  that,  while  removal  of  any 
portion  of  the  cerebellum  produces  interference  with  the  co- 
ordinating power  over  the  voluntary  muscles,  a  recovery  still 
takes  place,  after  a  lapse  of  time,  w^ithout  a  regeneration  of 
the  severed  portion ;  and  this  fact  alone  may  assist  us  to  ex- 
plain how  very  large  portions  of  the  cerebellum  may  be  gradu- 
ally destroyed  by  disease  and  the  remaining  part  acquire  the 
power  of  performing  the  normal  function  of  the  entire  gan- 
glion. Thus  Andral  *  reported  some  ninety  cases  of  disease  of 
the  cerebellum,  in  all  of  which  but  one  the  symptoms  were 
not  so  well  marked  as  to  support  the  theory  of  the  coordina- 
ting function  of  that  ganglion,  but,  in  many  of  these  cases,  as 
proven  by  Flint,'  the  circumstances  warranted  no  physiological 
deduction  whatever,  while  in  others  the  destruction  was  not 
more  extensive  than  had  frequently  been  made  on  animals  and 
recovery  of  the  coordinating  power  been  perfectly  regained. 

There  are  certain  facts  which  tend  to  show  some  connection 
between  the  semicircular  canals  of  the  ear  and  the  cerebellum, 
and  some  authors  have  endeavored  to  prove  that  the  effects  of 
section  of  the  cerebellum  are  due  in  great  measure  to  a  ver- 
tigo produced  similar  to  that  which  exists  in  the  so-called 
''  Meniere's  malady,"  which  is  dependent  upon  the  ear  mech- 
anism." The  experiments  of  Purkinje  on  the  human  cerebel- 
lum, by  passing  the  electric  current  through  the  head  from 
ear  to  ear,  showed  a  marked  type  of  vertigo  to  ensue  ;  and  an 
oscillation  of  the  eyes,  which  perform  all  varieties  of  move- 
ment, was  observed  by  Hitzig '  in  the  same  class  of  experiment. 

>  Op.  rit.  '  Op.  cit.  3  Qp   cit. 

*  "  Clinique  M6dicale  "  Discussed  and  quoted  in  full  in  the  "  Text-Book  of  Physiology," 
by  A.  Flint,  Jr. 

»  A.  Flint,  Jr.,  "  Text-Book  of  Physiology."    New  York,  1880. 
**  See  lecture  on  the  auditory  nerve.  '  Op.  cit. 


THE  CEEEBELLUM.  53 

Numerous  attempts  have  been  made  to  connect  the  cere- 
bellum with  the  sexual  functions,  but  the  results  of  later  ex- 
periments seem  to  locate  the  center  of  the  sexual  appetite  in 
the  spinal  cord,  somewhere  in  the  lumbar  region. 

Stimulation  of  the  cerebellum  has  been  observed  to  create 

kristaltic  movements  in  the  oesophagus  and  stomach,  as 
own  by  Budge, '  and  diabetes  has  been  observed  to  follow 
Ivanism  of  this  ganglion,  by  Eckhard.^  Some  relation  be- 
tween the  cerebellum  and  the  intestinal  tract  seems  to  be  fur- 
ther demonstrated  by  the  researches  of  Schiff,  who  observed 
that  after  injuries  to  the  peduncles  of  the  cerebellum  an  in- 
flammatory condition  of  the  intestine  followed,  which  was  of 
i  so  acute  a  type  as  to  be  accompanied  with  hsemorrhage. 
■  The  hypothesis  of  Mitchell,  that  the  cerebellum  is  the  store- 
r  house  for  nervous  force  for  use  in  emergencies,  is  plausible, 
om  the  remarkably  numerous  and  intimate  connections  of 
is  ganglion  with  other  parts  of  the  nervous  system,  but  can 
t,  as  yet,  be  considered  as  proven. 

The  cerebellum  is  remarkable  for  the  numerous  connections 
hich  exist  between  it  and  the  other  parts  of  the  nervous  sys- 
m.  Each  hemisphere  is  connected  with  the  caudate  nucleus 
d  the  hemisphere  of  the  cerebrum  of  the  opposite  side ; 
so,  by  special  fibers,  with  the  substance  of  the  pons  Varolii 
,nd  the  deeper  parts  of  the  meso-cephalon  (including  its  gray 
and  white  substance) ;  again,  with  the  medulla  oblongata  and 
the  spinal  cord  ;  and,  finally,  the  existence  of  commissural 
■bbers  connecting  the  hemispheres  of  the  cerebellum  is  prob- 
F  able.  The  close  relation  which  it  bears  (1),  to  the  medulla, 
L^hose  numerous  centers  are  doubtless  well  known  to  you  all ; 
l|^),  to  the  corpora  quadrigemina  and  its  center  governing  the 
I  vaso-motor  function,  and  having  a  possible  effect  upon  con- 
*  vulsive  movements  ;  (3),  to  the  ''  tegmentum  cruris,"  the  great 
I  sensory  tract ;  and  (4),  possibly  to  the  third,  fourth,  and  eighth 
nerves,'  which  have  been  traced  by  some  observers  to  this 

1  As  quoted  by  Foster, 

2  Eckhard's  "  Beitrage,"  1878. 

3  This  source  of  origin  is  as  yet  undecided. 


64  THE  BRAIN. 

ganglion,  certainly  seem  to  point  to  some  most  important 
functions  as  located  in  this  part  of  the  brain,  but  at  present 
little  can  be  positively  stated. 

The  intimate  relation  which  this  ganglion  bears  to  these 
parts  renders  it  a  matter  of  extreme  difficulty  to  discrim- 
inate, clinically,  between  the  results  of  disease  of  the  cerebel- 
lum and  the  effects  of  pressure  created  upon  adjacent  regions. 
When  we  consider  how  near  the  ganglia  of  vision,  the  points 
of  origin  of  the  third,  fourth,  and  sixth  nerves,  and  the  various 
nuclei  of  the  fourth  ventricle,  are  to  the  cerebellum,  we  can  un- 
derstand why  careful  observers  are  loath  to  accept  symptoms 
referable  to  the  eye  or  ear  as  positive  evidence  of  cerebellar 
disease,  and  why  vomiting,  so  often  present,  may  not  be  at- 
tributed with  equal  force  to  pressure  exerted  upon  the  me- 
dulla oblongata.  In  point  of  fact,  we  can  only  consider  the 
symptom  called  *' cerebellar  ataxia"  and  the  presence  of 
pain  in  the  occipital  region  as  of  positive  value  in  the  diag- 
nosis of  disease  of  this  ganglion,  and  even  these  may  often 
be  absent. 

When  the  loss  or  coordination  of  movement  dependent 
upon  disease  of  the  cerebellum  is  well  marked,  a  x)eculiarity 
of  attitude  in  walking,  called  by  some  authors  ''  titubation," 
is  developed.  The  patient  walks  with  the  feet  widely  sepa- 
rated; the  trunk  is  usually  bent  forward  and  sways  constantly; 
while  the  hands  and  arms  are  used  to  preserve  the  equilibrium 
of  the  body.  The  absence  of  all  spasmodic  movement,  of  tre- 
mor, and  of  the  want  of  harmony  between  antagonistic  groups 
of  muscles,  as  seen  in  true  ataxia,  tends  to  distinguish  it  from 
other  forms  of  disease.  The  upper  extremities  are  usually 
free  from  this  imperfect  coordination  ;  closing  of  the  eyes 
sometimes  increases  the  ataxic  symptoms,  but  often  fails  to 
affect  them  ;  the  recumbent  position  seems  to  arrest  all  symp- 
toms of  incoordination  ;  and  the  general  condition  closely  re- 
sembles that  of  alcoholic  intoxication.  The  recent  researches 
of  Nothnagel,  in  which  he  publishes  the  analysis  of  over  two 
hundred  and  fifty  cases,  seem  to  point  to  the  superior  vermi- 
form process  as  the  region  most  liable  to  produce  this  type  of 


THE  MEDULLA    OBLONGATA. 


65 


ataxia.  He  states  that,  if  the  patient  be  barefoot,  the  toes 
will  be  seen  to  be  in  active  motion  ;  that  the  patient  will  bring 
the  foot  to  the  floor,  sometimes  on 
the  heel  and  sometimes  on  the  ball, 
irrespective  of  intention,  thus  giv- 
ing an  irregularity  to  the  move- 
ments of  that  member ;  that  the 
body  will  sway  to  and  fro  ;  and 
that  the  legs  will  be  separated  in 
order  to  afford  additional  security 
in  the  standing  or  w^alking  position. 

THE  MEDULLA   OBLON-GATA. 

This  ganglion — the  upiDermost 
portion  of  the  spinal  cord — is  the 
true  nerve  center^  of  animal  life^ 
since  immediate  death  follows  se- 
vere injury  to  its  substance.  The 
fact  that  the  seventh,  eighth,  ninth, 
tenth,  eleventh,  and  twelfth  nerves 
arise  directly  from  this  ganglion, 
and  that  some  fibers  from  other 
of  the  remaining  six  cranial  nerves 
can  be  traced  to  the  cavity  of  the 
medulla  —  the  fourth  ventricle  — 
serves  to  explain  the  importance 
of  this  special  nerve  center.  In 
addition  to  the  special  influence  of 
the  medulla  oblongata  upon  the 
nerves  which  arise  from  it,  it  con- 
tains most  of  the  fibers  which  are 
distributed  to  the  other  parts  of 
the  encephalon,  and  thus  it  must 
transmit  both  the  motor  and  sen- 
sory impulses,  as  they  pass  from 
and  enter  the  cerebrum. 


VtltWVt  «\;t.iK\.Vt. 


Fig.  21. — Anterior  vieio  of  the  me- 
dulla oblongata.     (Sappey.) 

1,  infundibulum  ;  2,  tuber  cinereum ; 
3,  corpora  albicantia;  4,  cere- 
bral peduncle ;  6,  tuber  annu- 
lare ;  6,  ori-iin  of  the  middle  pe- 
duncle of  tlie  cerebellum ;  7, 
anterior  pyramids  of  the  medul- 
la oblongata  ;  8,  decuasation  of 
the  anterior  pyramids  ;  9,  oliva- 
ry bodies  ;  10,  restiform  bodies  ; 
11,  arciform  fiber's  ;  12,  upper 
extremity  of   the   spinal   cord ; 

13,  ligamentum   denticulatum  ; 

14,  14,  dura  mater  of  the  cord ; 

15,  optic  tracts  ;  16,  chiasm  of 
the  optic  nerves  ;  17,  motor  ocu- 
li  communis  ;  18,  patheticus  ;  19, 
fifth  nerve ;  20,  motor  oculi 
externus  ;  21,  facial  nerve;  22, 
auditory  nerve ;  23,  nerve  of 
Wrisbei'g ;  24,  glosso-pharynge- 
al  nerve  ;  25,  pneumogastric  ; 
26,  26,  spinal  accessory ;  27, 
sublingual  nerve;  28,  29,  30, 
cervical  nerves. 


66  THE  BRAm. 

The  medulla  is  possessed  of  a  large  amount  of  gray  mat- 
ter within  its  interior,  where  it  fonns  the  lining  of  the  cavity 
of  the  fourth  ventricle  ;  and  it  is  in  this  gray  matter  that  the 
action  of  the  medulla,  which  is  largely  reflex  in  character, 
takes  place.  From  the  nerves  which  spring  from  its  sub- 
stance, we  should  expect  that  these  reflex  acts  should  be 
chiefly  concerned  in  the  movements  of  the  facial  muscles  by 
means  of  the  seventh  nerve ;  with  audition  by  means  of  the 
eighth ;  with  deglutition  by  means  of  the  ninth ;  with  res- 
piration through  the  pneumogastric  or  tenth  nerve  ;  with 
phonation  and  the  action  of  the  heart  by  means  of  the  spi- 
nal accessory ;  and  with  lingual  movements  by  means  of  the 
hypo-glossal. 

Various  collections  of  gray  matter  in  the  floor  of  the  fourth 
ventricle  have  been  described  by  Lockhart  Clarke,  who  has 
connected  them  with  special  nerve  roots  ;  while  experimental 
investigation  has  also  determined  certain  special  pltysiologi- 
cal  centers  to  have  their  seat  within  the  substance  of  the 
medulla  oblongata.  As  the  former  centers  may  be  found  in 
almost  all  of  the  later  works  upon  descriptive  anatomy,'  an 
enumeration  only  of  the  physiological  centers  will  be  given, 
since  their  presence  adds  much  to  the  interest  which  per- 
tains to  the  medulla  as  a  reflex  ganglion. 

1.  The  respiratory  center^  which  governs  the  respu-atory 
acts,  in  response  to  sensory  impressions  transmitted  to  it  by 
means  of  the  pneumogastric  nerve. 

2.  The   vaso-motor  center ^^  which  seems   to  control  the 

*  The  f mirth  a'anial  nerve  is  said  to  arise  from  a  nucleus  on  the  outer  side  of  the  lo- 
cus coeruleus.  The  trigeminus  (fifth  cranial)  nerve  probably  arises  from  two  nuclei  situa- 
ted at  the  outer  angle  of  the  floor  of  the  fourth  ventricle ;  the  more  external  or  sensory 
nucleus  being  continuous  with  the  gray  tubercle  of  Rolando,  while  the  internal  or  motor 
nucleus  lies  close  to  the  sensory  nucleus,  but  nearer  the  median  line.  In  the  upper  half 
of  the  fourth  ventricle,  the  sixth  cranial  nerve  and  seventh  cranial  nerve  (facial)  take  their 
origin  from  distinct  nuclei.  The  auditor y  na-vc  (eighth  cranial)  has  two  separate  nuclei, 
as  has  the  fifth  cranial,  called  the  internal  and  external  auditory  nuclei,  which  arc  situated 
below  those  of  the  trigeminus  nerve  and  above  the  nucleus  for  the  glosso-pharyngeal 
nerve.  Finally,  in  the  lower  half  of  the  fourth  ventricle,  close  to  the  postero-mcdian  fis- 
sure, are  found  separate  nuclei  of  origin  for  the  glosso-pharyngeal,  pneumogastric,  the 
accessory  portion  of  the  spinal  accessory,  and  the  hypo-glossal  nerves. 

'  The  upper  limit  of  this  center  in  the  rabbit  is  placed  by  Owsjannikow  (Ludwig's 


CENTERS  OF  TEE  MEDULLA.  67 

caliber  of  the  larger  blood-vessels,  by  means  of  efferent  im- 
pulses, transmitted  chiefly  through  the  splanchnic  nerves, 
which  affect  the  muscular  coat  of  the  vessels  of  the  thorax, 
abdomen,  and  pelvis. 

3.  The  cardio-inhihitory  center^  by  which  the  heart  is 
arrested  in  diastole,  or  held  Under  control,'  in  response  to 
sensory  impressions  carried  to  the  medulla  from  other  sources 

Wm  means  of  sensory  nerves. 

!■  4.  The  center  for  deglutition,  w^hich  controls  both  the 

^!Scond  and  third  stages  of  that  act,  or  from  the  time  when  the 

'.    bolus  passes  the  isthmus  of  the  fauces." 

5.  The  center  for  the  movements  of  the  oesophagus  and 
the  stomachy  with  its  allied  center  for  the  control  of  the 
mechanism  of  the  act  of  vomiting. 

6.  The  diabetic  center ^^  which,  when  stimulated,  produces 
a  saccharine  condition  of  the  urine. 

7.  The  salivary  center,''  which,  upon  excitation,  tends  to 
increase  the  flow  of  the  saliva,  and  possibly,  also,  the  pancre- 
atic fluid  and  the  other  digestive  juices. 

"  Avbeitem,"  ISVl)  at  about  2  mm.  below  the  tubercula  quadrigemina,  and  its  lower 
limit  at  about  4  or  5  mm.  above  the  calamus  scriptorius.     Clarke  locates  it  near  to  the 
I     origin  of  the  facial  nerve,  and  claims  that  large  multipolar  cells  can  be  detected  in  the 
vaso-motor  area ;  while  Dittmar  (Ludwig's  "  Arbeitem,"  1873)  places  it  chiefly  in  the  lat- 
,     eral  columns,  after  the  fibers  have  been  given  off  to  the  decussating  pyramids.     Besides 
!     this  vaso-motor  center  in  the  medulla  oblongata,  other  parts  of  the  spinal  cord  unques- 
tionably exert  a  positive  vaso-motor  influence,  causing  constriction  or  dilatation  of  the 
blood-vessels. 

^  If  the  mesentery  of  a  frog  be  exposed,  and  a  slight  tap  be  given  it  by  the  handle  of 
the  scalpel,  the  heart  will  at  once  cease  to  beat,  but  will  soon  resume  its  function.     This 
experim.ent,  coupled  with  many  others  of  interest,  seems  to  point  definitely  to  the  medulla 
as  the  seat  of  mediation  between  affei'ent  sensory  impulses  and  efferent  inhibitory  im- 
pulses upon  the  heart. 
^^  '-^  This  subject  will  be  found  discussed,  at  some  length,  in  the  pages  devoted  to  the 
iBchanism  of  deglutition,  as  well  as  the  movements  of  the  oesophagus. 
IB  8  The  diabetic  center,  as  marked  out  by  Eckhard,  corresponds  closely  to  that  defined 
HB  Owsjannikow  as  the  vaso-motor  area.     Pricking  of  this  center  in  a  well-fed  rabbit  will 
"produce  a  considerable  amouut  of  sugar  in  the  urine,  within  an  hour  or  two  following  the 
;     experiment.     This  effect  is  poorly  marked  in  animals  whose  livers  have  been  deprived  of 
:     glycogen  by  starvation. 

I  *  The  flow  of  saliva  is  apparently  a  reflex  act  dependent  upon  afferent  impulses  per- 

I  ccived  through  the  gustatoiy  branch  of  the  fifth  cranial  nerve,  the  efferent  impulse  being 
transmitted  by  means  of  the  chorda  tympani  branch  of  the  facial  nerve.  It  is  this  func- 
tion of  the  latter  nerve  that  is  considered  by  some  physiologists  as  explanatory  of  the  effect 
of  the  chorda  upon  taste.    (See  pages  descriptive  of  the  facial  nerve  and  its  branches.) 


68  THE  BEAIK 

Finally,  it  is  proven  tliat  tlie  medulla  oblongata  in  animals 
plays  a  part  in  the  coordination  of  movement,  and  it  may  be 
considered  probable  that  in  man  the  same  property  is  like- 
wise possessed  ;  but  it  is,  unfortunately,  incapable  of  demon- 
stration, as  the  death  of  the  individual  usually  follows  any 
traumatic  lesion  of  this  ganglion. 

The  clinical  aspects  of  the  medulla,  its  minute  anatomy, 
and  its  physiological  construction,  will  be  more  fully  consid- 
ered in  connection  with  the  spinal  cord  and  cranial  nerves. 

THE  SURGICAL  BEARINGS  OF  CEREBRAL  TOPOGRAPHY. 

In  the  year  1861,  Broca  invented  a  scientific  method  of  de- 
termining the  relations  of  different  parts  of  the  cerebrum  to 
the  exterior  of  the  skull,  which  consisted  of  driving  pegs 
through  the  skulls  of  animals  and  of  cadavers,  holes  having 
been  previously  bored  through  the  bone  in  order  to  prevent 
fracture  and  injury  to  surrounding  parts.  The  skull-cap  was 
then  removed  with  extreme  care,  and  the  convolutions  which 
were  wounded  were  thus  determined.  It  was  discovered  by 
this  observer  that  the  fissure  of  Rolando^  whose  relation  to 
the  coronal  suture  was  then  unknown,  lay  obliquely,  and 
that  its  upper  extremity  could  be  placed,  with  great  accuracy 
in  man,  at  a  point  situated/br^^  millimetres  heJilnd  the  coro- 
nal suture.  This  fissure  was  i)articularly  studied  on  account 
of  its  relation  to  the  motor  region  of  the  cortex^  and  its  exact 
bearing  to  the  exterior  of  the  skull  was  therefore  of  great  im- 
portance. The  same  observer  was  also  able  to  prove  that  the 
external  par  ieto-occipital  fissure  of  the  cerebrum  lay  under  the 
lambdoid  suture  of  the  cranium.  In  1873,  the  experiments  of 
Heftier  and  Bischoff  were  added  to  those  of  Broca,  while  Tur- 
ner followed  with  his  researches  in  1874,  and  Fere  in  1875. 
The  drawings  which  Turner  furnished  were  admirable  in  their 
way,  but  are,  to  my  mind,  hardly  adapted  to  the  purposes  of 
the  surgeon,  since  the  guides  which  the  bony  prominences  of 
the  skull  afford  are  not  brought  into  such  prominence  as  to  be 
readily  comprehended  by  the  casual  reader.    If  the  sui'geon  is 


SURGICAL    GUIDES  OF  CRANIUM.  69 

to  utilize  the  valuable  researches  of  the  investigators  above 
named  (and  several  most  brilliant  surgical  operations  have 
already  been  performed  from  the  light  which  the  newly  ac- 
quired knowledge  of  the  topography  of  the  cerebrum  has  af- 
forded), certain  bony  prominences  of  the  skull  must  be  des- 
ignated, as  of  importance,  as  guides  to  the  special  convolu- 
tions and  fissures  of  the  brain.  ISTow,  there  is  one  line  which 
is  easily  drawn  upon  the  head  of  the  living  subject  (the  alve- 
o-condyloid  plane  of  Broca),  upon  which  perpendicular  lines 
may  be  described,  intersecting  certain  bony  points,  which 
lines  can  be  utilized  as  guides  to  parts  whose  situation  is 
now  positively  known.  This  base  line  should  be  a  straight 
one,  and  should  intersect  the  tip  of  the  mastoid  process  and 
the  line  of  the  cusps  of  the  teeth  of  the  upper  jaw.  ^ 

This  is  the  natural  posture  of  the  human  skull,  when  the 
pper  jaw  is  removed  and  the  skull  placed  upon  a  table  ; 
nee  it  is  a  plane  admirably  adapted  for  the  study  of  the 
ides  (which  will  be  given),  upon  the  skeleton,  in  the  ofiice 
each  practitioner,  previous  to  an  operation.  Furthermore, 
skull  can  easily  be  painted  upon  its  exterior  so  as  to  bring 
e  lines,  designated  as  important,  into  prominence,  and  so 
sist  the  surgeon  in  the  review  of  those  points  which  pos- 
sess special  value.  The  contribution  of  Fere  is,  to  my  mind, 
e  best  of  all  the  authors  named,  since  it  presents  the  points 
^ost  needed  by  the  surgeon  in  a  practical  way ;  and  the 
resume  of  his  guides  is  so  tersely  and  clearly  stated  by  my 
friend  Professor  Seguin  that  it  would  be  useless  to  attempt  to 
improve  upon  it.  It  will  be  perceived  in  the  plate,  intro- 
duced to  make  these  guides  more  clear  than  a  mere  verbal 
description,  that  the  line  described,  viz.,  the  alveolo-condy- 
loid  plane  of  Broca,  is  used  as  a  base  line  upon  which  to 
erect  perpendiculars  at  distances  which  can  be  accurately 
measured  upon  it ;  and  that  these  perpendicular  lines  inter- 

^  This  author  places  the  line  as  intersecting  the  condyle  of  the  occipital  bone  ;  but,  as 
this  can  not  be  felt  in  the  living  subject,  and  as  it  corresponds  to  the  tip  of  the  mastoid 
process,  I  have  modified  the  guide  so  as  to  simplify  its  exact  situation  upon  the  exterior 
of  the  skull. 

7 


r    set 


70 


THE  BEAiy, 


sect  certain  regions  which,  from  facts  previously  recorded, 
are  of  the  greatest  importance.  I  quote  the  resume  of  Seguin ' 
upon  this  special  department  of  cerebral  localization  : 


4  A 

Fig.  22. —  Outline  of  skull  resting  upon  the  alveolo-condyloid  plane  of  Broca.    (Modified  from 
Topinard's  "  Anthropology  "  by  Seguin.) 

Vertical  line  a,  or  auriculo-bregmatic.  Line  9-10,  drawn  parallel  to  the  plane  of  Broca. 
Upon  this  line,  at  a  distance  of  45  mm.  posterior  to  the  bregma,  a  vertical  line,  1-2, 
will  pass  through  the  upper  (inner)  end  of  the  fissure  of  Rolando,  ft,  6,  and  through 
the  posterior  extremity  of  the  thalamus  opticus  (c).  A  third  vertical  line,  3-4,  drawn 
at  30  mm,  forward  of  the  bregma,  will  pass  through  the  fold  of  the  third  frontal 
gyrus  (a),  and  through  the  head  of  the  nucleus  caudatus  {d).  The  horizontal  line, 
7-8,  at  45  mm.  below  the  bregma  (scalp),  indicates  the  upper  limit  of  the  central 
ganglia.  The  third  horizontal  line,  5-6,  passing  through  the  external  angular  pro- 
cess of  the  frontal  bone  and  the  occi  pi  to-parietal  junction,  approximately  indicates 
the  course  of  the  fissure  of  Sylvius,  and  serves  for  measurements.  At  18  or  20  mm. 
behind  the  external  angular  process  on  this  line  is  the  speech  center  of  Broca  ;  5  to 
8  mm.  behind  the  intersection  of  3-4  and  5-6  is  the  beginning  of  the  fissure  of  Sylvius, 
and  at  28  or  30  mm.  behind  this  intersection  is  the  lower  end  of  the  fissure  of  Ro- 
lando, 6,  6,  placed  a  little  too  far  back  in  the  cut.  At  x  (near  6),  near  the  median 
line,  is  the  location  of  the  occipito-parietal  fissure. 

'^1.  A  vertical  line  (a)  drawn  from  the  alveolo-condyloid 
plane,  through  the  external  auditory  meatus  upward,  will  pass 
through  or  veiy  near  to  the  bregma,  or  line  of  junction  of  the 
frontal  and  parietal  bones  at  the  vertex  ;  it  passes  through 
the  anterior  (lower)  extremity  of  the  fissure  of  Rolando. 

*'  2.  If,  from  the  upper  end  of  this  vertical  line  a,  we  mea- 
sure a  distance  of  45  mm."  backward  toward  the  occiput  and 

'  "Medical  Record,"  1878. 

'  A  millimetre  is  about  one  twenty-fifth  of  an  inch. 


I 


SURGICAL   GUIDES  OF  CRANIUM.  Yl 


draw  a  descending  vertical  line  (1-2),  we  mark  out  the  location 
of  two  most  important  parts  of  the  cerebrum,  viz.,  the  poste- 
rior extremity  of  the  fissure  of  Rolando  [at  h\  and  the  poste- 
rior limit  of  the  thalamus  opticus  in  the  hemisphere  [at  c]. 

''3.  To  conclude  with  the  occipital  end  of  the  skull ;  if  we 
can  make  out  with  the  finger  the  lambdoid  suture  at  the  medi- 
an line,  we  thus  learn  the  situation  of  the  subjacent  occipito-pa- 
rietal  fissure,  which  separates  the  parietal  and  occipital  lobes. 

' '  4.  The  last  vertical  line  worth  noting  is  one  drawn  at  a 
distance  of  30  mm.  forward  of  the  auriculo-bregmatic  line. 
This  vertical  line  (3-4)  will  pass  through  the  middle  fold  of 
the  third  frontal  convolution  (just  forward  of  the  speech  cen- 
ter), and  will  also  indicate  the  anterior  limit  of  the  central 
cerebral  ganglia,  viz.,  the  head  of  the  nucleus  caudatus  in  the 
hemisphere  [at  d\. 

''  5.  The  upper  level  of  the  central  cerebral  ganglia  may  be 
quite  exactly  indicated  by  an  horizontal  line  drawn  at  a  dis- 
tance of  45  mm.  below  the  surface  of  the  scalp,  at  the  bregma, 
(or  35  below  the  surface  of  the  bare  skull  at  the  same  point). 
This  line  (7-8)  also  runs  across  the  middle  regions  of  the  mo- 
tor district  of  the  convolutions,  containing  centers  for  the  face 
and  upper  extremities. 

^'6.  The  external  angular  process  of  the  frontal  bone, 
not  difficult  to  define  in  the  living  subject,  is  the  starting- 
point  of  another  horizontal  line  {5-6),  whose  posterior  ex- 
tremity passes  a  little  below  the  lambdoid  suture.  Upon  this 
horizontal  line  we  can,  by  measurement,  determine  the  loca- 
tion of  certain  parts.  Thus,  at  a  distance  of  18  or  20  mm.  be- 
hind the  external  angular  process,  lies  the  folded  part  of  the 
third  frontal  convolution  (a).  This  point,  in  many  heads,  will 
correspond  to  the  vertical  line  3-4. 

"7.  The  situation  of  the  fissure  of  Sylvius  may  be  approx- 
imately ascertained  in  the  following  manner :  Its  middle  por- 
\  tion  extends  horizontally,  almost  under  the  upper  part  of  the 
squamous  suture,  which  in  the  living  subject  is  to  be  found  a 
little  below  the  horizontal  line  5-6.  The  anterior  extremity  or 
beginning  of  the  fissure  of  Sylvius  is  a  little  below  this  hori- 


72  THE  BRAIK 

zontal  line,  at  a  distance  of  some  5  to  8  mm.  posterior  to  the 
intersection  of  3-4  and  5-Q^  and  consequently  about  22  or  25 
mm.  anterior  to  the  auric ulo-bregmatic  line  a.  Lastly,  accord- 
ing to  Turner,  the  parietal  eminence  almost  always  overlies  the 
supra-marginal  gyrus  (P',  Fig.  23),  consequently  the  posterior 
extremity  of  the  fissure  of  Sylvius  is  likewise  in  this  vicinity. 

''8.  The  angular  gyrus  is  to  be  found  below  and  behind 
the  parietal  eminence,  a  little  above  the  horizontal  line  drawn 
from  the  external  angular  process  {5-Q). 

"  9.  The  anterior  (lower)  end  of  the  fissure  of  Rolando  lies 
at  a  distance  of  28  or  30  mm.  behind  the  line  3-4,  and  a  little 
above  5-6.  It  is,  therefore,  a  few  millimetres  anterior  to  tlie 
vertical  line  a." 

With  this  plate  as  a  guide,  and  with  a  thorough  knowledge 
of  the  facts  comprised  in  previous  pages  of  this  chapter,  it  is 
not  out  of  the  bounds  of  possibility  to  definitely  locate  the 
existence  of  lesions  in  certain  portions  of  the  human  brain, 
to  map  out  their  situation  upon  the  exterior  of  the  skull, 
and  to  reach  them  with  surgical  means  of  relief,  provided  the 
case  be  one  which  would  justify  such  a  measure.  When 
Broca  has  been  successful  in  trephining  directly  over  an  ab- 
scess of  the  third  frontal  convolution,  w^hich  was  suspected, 
and  when  successful  cases  have  been  reported  of  trephining 
of  the  skull  for  fragments  of  the  inner  plate  which  were  com- 
pressing the  ascending  gyri  of  the  frontal  and  parietal  lobes, 
thus  causing  paralysis,  have  we  not  every  reason  to  hope  that 
the  day  is  coming  when  the  rules  governing  this  operation 
will  be  those  based  upon  science  rather  than  upon  empiricism, 
and  when  the  surgeon  will  owe  his  success  to  the  researches 
of  the  physiologist  and  the  labors  of  the  pathologist  ? 

There  are  certain  suggestions,  which  may  be  thrown  out  in 
this  connection,  which  are  safe  ones  to  follow  in  cases  where 
the  propriety  of  surgical  relief  is  called  into  question.  These 
may  be  stated  in  the  form  of  propositions,  which  are  of  neces- 
sity based  upon  the  contents  of  the  previous  lectures. 

1.  If  the  injury  sustained,  provided  the  case  in  question 
be  one  of  a  traumatic  origin,  be  situated  over  the  motor  area 


RULES  FOR   TREPHINING.  73 

of  the  cortex,  tlie  presence  of  ancesthesia  in  combination  with 
motor  hemiplegia  is  a  contraindication  to  attempts  at  surgical 
relief.  This  symptom  (anaesthesia)  probably  indicates  some 
injury  to  the  posterior  third  of  the  internal  capsule,  or  to  the 
white  substance  of  the  hemispheres  ;  hence  the  lesion  is  proba- 
bly too  extensive  to  be  relieved  by  trephining. 

2.  If  the  sensory  region  of  the  cortex  be  involved,  and 
ralysis  or  convulsive  movements  occur,  an  operation  is  con- 

traindicated  ;  since  the  lesion  has  either  been  so  extensive 
as  to  ex:tend  to  the  motor  area,  or  has  torn  or  compressed  the 
cerebrum  at  a  point  removed  from  the  apparent  seat  of  injury. 

3.  The  occurrence  of  paralysis  on  the  same  side  as  that 
upon  which  the  injury  was  received  is  always  a  contraindica- 
tion to  any  surgical  procedure  at  the  seat  of  injury,  since  it 
usually  indicates  some  lesion  of  the  opposite  side,  probably 

(ependent  upon  transmitted  force  {contre-coup). 
4.  The  completeness  of  the  paralysis  maybe  often  taken 
I  a  guide  to  the  amount  of  injury  done  to  the  cerebrum  :  if 
tne  paralysis  be  very  profound,  the  chance  of  success  from 
trephining  is  extremely  small,  since  the  injury  has  probably 
affected  parts  deeper  than  the  cortex  centers. 

5.  The  appearance  of  paralysis  of  any  of  the  special  nerves 
of  the  cranium^  or  the  development  of  the  symptoms  due  to 

1    lesions  of  the  base  of  the  brain  or  of  the  basal  ganglia,  such  as 

:    the  Cheyne-Stokes  respiration,'  choked  disk,  and  vomiting, 

may  be  regarded  as  contraindications  to  surgical  interference. 

6.  When  an  injury  to  the  skull  is  followed,  after  a  lapse 
jj  of  some  weeks,  by  aphasia^  the  diagnosis  of  abscess  of  the 
I  base  of  the  third  frontal  convolution,  or  possibly  involving 
li   the  island  of  Reil  or  the  white  substance  situated  between  the 

third  frontal  convolution  and  the  basis  of  the  cerebrum,  may 

be  safely  made. '     In  such  a  case,  the  operation  of  trephining, 

^^  performed  by  Broca,  affords  a  strong  probability  of  relief. 

HI    7.  Cases  of  injury  which   are  followed  immediately  hy 

^^phasia  are  strongly  diagnostic  of  either  a  spicula  of  bone  or 

He   ^  A  respiration  whose  rhytlim  steadily  increases,  and  then  decreases,  in  a  short  inter- 
P&l  of  time ;  described  in  1818  by  Cheyne,  and  by  Stokes  in  1846. 
H  ^  Authorities  are  not  all  in  accord  with  this  statement. 


74  THE  BRAIN. 

the  pressure  of  a  clot  in  the  neighborhood  of  the  center  of 
Broca.  The  f  oraier  condition  would  be  strongly  in  support  of 
surgical  interference,  since  it  would  probably  continue  to  cre- 
ate pressure  or  irritation  until  removed,  while  the  pressure  of 
a  clot  might  also  be  relieved  by  trephining. 

8.  If  the  region  over  the  fissure  of  Rolando  be  subjected  to 
apparent  injury,  and  the  symptoms  of  some  of  the  special 
types  of  monoplegia  appear  (affecting  the  muscles  of  the  face, 
arm,  leg,  or  any  of  these  combined '),  or  even  the  occurrence 
of  a  slight  form  of  hemiplegia  follow,  successful  trephining 
may  be  reasonably  expected.  The  presence  of  anaesthesia,  as 
before  mentioned,  would,  however,  still  be  a  strong  contra- 
indication to  such  a  step,  since  it  would  prove  that  the  lesion 
was  probably  of  too  deep  a  character  to  be  benefited  by  the 
simple  removal  of  a  button  of  bone,  as  the  posterior  third  of 
the  internal  capsule  would  probably  be  found  to  be  impah'ed. 
It  must  be  also  remembered  that  the  motor  paralysis,  of  what- 
ever kind  it  may  be,  must  be  confined  to  the  side  of  the  body 
opposite  to  the  seat  of  injury,  if  benefit  is  to  be  expected. 
The  type  of  monoplegia  which  exists  may  often  be  used  as 
a  guide  to  determine  the  extent  of  the  lesion  as  well  as  its 
situation.' 

GENERAL  SUMMARY  OF  THE  BRAIN-,   AND  ITS  CLINICAL  RELA- 
TIONS. 

We  have  now  considered  the  various  parts  of  the  brain 
somewhat  in  detail,  and  have  noted  some  of  the  points  of 
clinical  interest  which  each  presents.  Many  anatomical  tenns 
have,  however,  been  employed  at  various  times,  which  may 
be  a  source  of  embarrassment  to  you,  provided  you  are  not 
perfectly  familiar  with  the  anatomical  construction  of  the 
encephalon.  I  have  deemed  it  advisable,  therefore,  to  hastily 
review  such  anatomical  points  as  seem  important  for  you  to 
grasp  (as  a  preparation  for  clinical  study),  before  I  bring  this 

'  See  page  45  of  this  volume. 

'  Sec  the  motor  centers  situated  in  the  asccndinp;  frontal  and  parietal  convolutions, 
page  39  of  this  volume,  and  the  various  forms  of  monoplcj^ia  described  in  the  early  pages 
of  this  chapter. 


GENERAL  SUMMARY.  75 

subject  to  a  close,  and  pass  to  tlie  other  portions  of  the  ner- 
vous system. 

The  gray  matter  of  the  exterior  surface  (the  cortex)  of  the 
cerebrum  and  cerebeUum  forms  a  true  ganglionic  mass,  which 
is  spread  out  over  a  large  expanse  of  surface,  but  which,  like 
all  ganglionic  masses,  consists  of  nerve  cells,  nerve  fibers, 
blood-vessels,  and  the  connective  tissue  of  the  brain — the  neu- 
roglia. The  rapid  growth  of  the  requirements  which  advanc- 
ing age  demands  of  this  gray  matter  of  the  cortex  demands  a 
larger  expanse  of  surface  than  the  Interior  of  the  skull  would 
admit  of,  provided  this  gray  matter  was  smoothly  distrib- 
uted ;  hence  the  presence  of  convolutions,  or  "gyri,"  and  the 
depressions  between  them,  the  ''sulci,"  which  are  much 
more  marked  in  the  adult  than  in  the  infant.  It  should  be 
understood  also  that  the  gray  matter  of  the  cortex  is  of 
nearly  the  same  thickness  in  all  portions,  and  that  it  there- 
fore lines  the  sulci,  as  well  as  covers  the  convolutions.  The 
foldings  of  the  gray  cortical  layer  are,  however,  not  of  a 
uniform  character;  hence  a  difference  in  the  depth  of  the 
depressions  between  them.  It  lias  been  found  necessary  to 
name  some  of  the  more  prominent  fissures  or  ''sulci,"  in  or- 
der to  have  certain  easily  defined  landmarks,  for  the  purpose 
of  more  readily  designating  the  separate  convolutions,  which 
are  apparently  arranged  as  a  confused  mass,  but  which  are 
found  to  be  uniformly  developed  and  constant  in  their  situation. 

The  admirable  monograph  of  Ecker  on  the  topography  of 
the  cerebral  convolutions  and  the  researches  of  Ferrier '  and 
Dalton''  enable  us  so  to  group  these  various  gyri  and  fissures 
as  to  assist  us  in  retaining  them  in  our  memories  ;  while  such 
a  knowledge  is  indispensable  to  a  complete  understanding 
either  of  the  images  w^hich  have  preceded  or  of  those  which 
are  to  follow. 

We  may  start,  then,  with  the  statement  that  we  have  to 
know  the  situation  of  four  lobes,  four  lobules,  and  four  prin- 
cipal fissures  or  "  sulci."     These  may  be  given  as  follows  : 

'  Op.  cit. 

2  "  Text-Book  of  Physiology."     H.  C.  Lea,  Philadelphia,  1876. 


76 


THE  BEAIK 


The  fofr  sulci  are 


The  foue  lobes  are: 


C  Ascending  limb  of  the  fissure  of  Sylvius. 
J  Horizon  till  limb  of  the  fissure  of  Sylvius. 
J  The  fissure  of  Rolando. 
[  The  external  parieto-occipital  fissure. 

The  frontal  lobe. 

The  parietal  lobe. 

The  temporo-sphenoidal  lobe. 

The  occipital  lobe. 


(The  lobulus  centralis  (the  island  of  Reil). 
The  lobulus  para-centralis. 
Ihe  lobulus  cuneus. 
The  lobulus  quadratus. 


Fig.  23. — Lateral  view  of  the  human  brain,  showing  its  lobes  and  fissures.    (After  Ferrier.) 

F,  frontal  lobe ;  P,  parietal  lobe ;  0,  occipital  lobe ;  T,  temporo-spbenoidal  lobe ;  S,  fis- 
sure of  Sylvius  ;  S',  horizontal  portion  ;  S",  ascending  portion  of  the  same  ;  c,  sulcus 
centralis  or  fissure  of  Rolando ;  A,  anterior  central  convolution  or  ascending  frontal ; 
B,  posterior  central  convolution  or  ascending  parietal ;  Fj,  superior;  Fj,  middle;  Fs, 
inferior  frontal  convolution  ;  fi,  superior;  fj,  inferior  frontal  sulcus;  f  3,  sulcus  pr«?- 
centralis  ;  Pi,  superior  parietal  lobule,  or  postero-parietal  lobule  ;  Pa,  inferior  parietal 
lobule,  viz. :  Pa,  gyrus  supra-marginalis  ;  P3',  gyrus  angularis ;  p,  sulcus  intra-pa- 
rietalis ;  c,  ni,  termination  of  the  calloso-marginal  fissure ;  d  first,  O2  second,  Os 
third  occipital  convolutions  ;  po,  parieto-occipital  fissure  ;  o,  sulcus  occipitalis  trans- 
versus ;  Oa,  sulcus  occipitalis  longitudinalis  inferior ;  Ti  first,  Ta  second,  T3  third 
temporo-sphenoidal  convolutions  ;  ti  first,  ta  second  temporo-sphenoidal  fissures. 


GENERAL  SUMMARY.  ^7 

Let  US  now  consider,  in  a  superficial  way,  the  points  of 
value  which  pertain  to  each  of  these  special  localities,  noting 
such  guides  as  may  suggest  themselves  to  aid  memory,  and 
following  Fig.  23  as  we  progress,  in  order  to  make  the  descrip- 
tion more  clear  than  w^ords  alone  could  do. 


I 


THE   PRINCIPAL  FJSSUPvES   OF  THE   CEREBRUM. 


The  ascending  limb  of  the  fissure  of  Sylvius  {s^')  passes  in 

^iront  of  the  island  of  Reil  and  among  the  frontal  convolutions. 

H*     The  horizontal  limb  of  the  fissure  of  Sylvius  {s')  passes 

backward  behind  the  island  of  Reil,  and  separates  the  tem- 

poro-sphenoidal  lobe  from  the  frontal   and  parietal  lobes, 

which  lie  adjoining  it. 

The  fissure  of  Sylvius  has  a  surgical  and  medical  impor- 
tance from  the  fact  that  it  contains  the  middle  cerebral  artery, 
I  which  is  particularly  liable  to  obstruction  from  the  impaction 
t  of  an  embolus,  especially  upon  the  left  side  of  the  body  ;  which 
I  accident  is  liable  to  be  followed  by  aphasia,  since  the  center 
I    of  speech  is  supplied  by  this  artery. 

The  fissure  of  Rolando  (c)  separates  the  frontal  from  the 
parietal  lobe  ;  it  passes  downward  and  forward  from  the  up- 
per part  of  the  cerebrum  till  it  almost  joins  the  horizontal 
limb  of  the  Sylvian  fissure.  It  is  an  important  surgical  region 
(see  page  40). 

The  external  parieto-occipital  fissure  (po)  separates  the 
parietal  and  occipital  lobes,  hence  its  name.  It  is  continued 
upon  the  inner  surface  of  the  cerebrum  as  the  ''internal  pari- 
eto-occipital fissure."  It  is  very  variable  in  its  extent,  and  is 
sometimes  scarcely  recognizable. 


THE  LOBES  OF  THE   CEREBRUM. 


The    FROTCTAL   LOBE  (F)  is  contained  in  the  anterior 
fossa   of    the    skull.      It    presents    four    convolutions, '    or 

^  See  Figs.  12  and  23. 

2  The  frequent  occurrence  of  an  accessory,  or  fourth  fronted  convolution  in  the  brains 
of  criminals  is  noted  by  Benedikt  ("  Centralbl.  f.  d.  med.  Wiss.,"  Nov.,  1880).     It  was 


78  TEE  BRAIN. 

"gyri,"  wMcli  are  specially  named.  These  may  be  thus 
stated : 

The  ascending  frontal  convolution.^  or  gyrus  (A),  which  lies 
anterior  to  the  fissure  of  Kolando,  being  separated  from 
the  ascending  parietal  convolution  by  that  fissure. 

The  superior  frontal  convolution,  or  gyrus  (F,),  which  joins 
the  ascending  gyrus,  passing  transversely  across  the  fron- 
tal lobe. 

The  middle  frontal  convolution.^  or  gyrus  (Fg),  passing  paral- 
lel to  the  superior. 

The  inferior  frontal  convolution.,  or  gyrus  (F3),  lying  below 
the  middle,  but  still  running  transversely  across  the  fron- 
tal lobe. 

The  PARIETAL  LOBE '  (P)  has  also  four  convolutions,  or  gyri, 
called  the  ascending,  the  supra-marginal,  the  parietal  lobule, 
and  the  angular  gyrus. 

The  ascending  parietal  convolution  (B)  lies  back  of  the  fissure 
of  Kolando,  being  separated  from  the  ascending  frontal 
convolution  by  means  of  that  fissure. 

The  supra-marginal  convolution  (P,),  th^  parietal  lobule  (P,), 
and  the  angular  gyrus  (P/),  being  the  other  three  con- 
volutions of  the  parietal  lobe,  are  situated  behind  the 
ascending  parietal  convolution. 

The  TEMPORO-SPHENOiDAL  LOBE  (T)  presents  three  well- 
marked  convolutions,  which  run  in  an  antero-posterior  direc- 
tion.    They  are  named  as  follows  : 

The  superior  temporo- sphenoidal  convolution  (T,),  which  lies 
below  the  horizontal  limb  of  the  Sylvian  fissure,  and 
which  is  continuous  behind  with  the  parietal  lobe. 

found  to  exist,  more  or  less  completely  developed,  in  the  majority  of  brains  of  this  class 
in  his  possession.  It  originated  usually  by  a  liifurcation  of  the  middle  frontal  convolu- 
tion, occasionally  by  a  bifurcation  of  the  superior  frontal  convolution.  Other  points  of 
interest  are  presented,  including  the  occurrence  of  a  ffth  convolution.  These  facts  the 
author  regards  as  the  expression  of  a  great  pathological  law,  that  atypical  structure  is  the 
chief  agent  in  the  production  of  atypical  (morbid)  performance  of  function. 

^  The  letters  in  parentheses  refer  to  Fig.  2:i,  although  Fig.  12  will  perhaps  give  a  betr 
tor  conception  of  the  convolutions  to  the  reader. 


GENERAL  SUMMARY. 


79 


The  middle  temporo-spJienoidal  convolution  (T,),  wMch.  be- 
comes continuous  with  the  angular  gyrus,  and  is  con- 
nected to  the  middle  occipital  convolution. 

The  inferior  temporo-spJienoidal  convolution  (Tg),  seen  on  the 
under  surface  of  the  cerebrum,  and  connected  with  the 
third  occipital  convolution. 

The  OCCIPITAL  LOBE  (O)  presents  three  badly  defined  con- 
volutions, which  are  superimposed  upon  each  other,  and 
which  lie  in  a  more  or  less  antero-posterior  direction. 

The  superior  occipital  convolution  (O,)  is  connected  with  the 

parietal  lobule. 
The  middle  occipital  convolution  (O,)  is  connected  with  the 

angular  gyrus,  and  also  with  the  middle  temporo-sphe- 

noidal  convolution. 
The  inferior  occipital  convolution  (O3)  is  connected  with  the 

inferior  temporo-sphenoidal  convolution. 


Fig.  24. — A  diagram  of  the  ccrehtim  in  longitudinal  median  section.     (After  Dalton.) 

1,  calloso-marginal  fissure;  2,  parieto-occipital  fissure  ;  3,  calearine  fissure:  A,  third  ven- 
tricle ;  B,  fifth  ventricle  ;  D,  anterior  crura  of  fornix ;  C,  cuneus  (occipital  lobule) ; 
Q,  praecuneus  (lobulus  quadratus) ;  P,  para-central  lobe ;  C  C,  corpus  callosum  ;  F, 
gyrus  fornicatus. 

THE  LOBULES  OF  THE  CEREBRUM.^ 

The  lobulus  centralis,  or  the  island  of  Eeil,  is  deeply  sit- 
uated at  the  bottom  of  the  fissure  of  Sylvius,  between  the 

1  See  Fiirs.  23  and  24. 


80  THE  BRAIK 

frontal  and  the  temporo-sphenoidal  lobes.  It  presents  five  or 
six  convolutions,  which  are  nearly  straight,  and  which  are 
directed  outward  and  upward.  This  portion  of  the  cerebrum 
is  probably  connected  with  the  faculty  of  speech.  It  is  sup- 
plied with  blood  by  the  middle  cerebral  artery.  It  can  not 
be  well  shown  in  a  plate,  on  account  of  its  situation. 

The  para-ccntral  lobule  (P)  is  found  on  the  internal  sur- 
face of  the  cerebrum,  in  front  of  the  lobulus  cuneus.  It  is 
of  great  importance,  from  a  clinical  point  of  view,  since  we 
know  that  disease  of  this  convolution  is  followed  by  second- 
ary degeneration  of  the  motor  tract  of  the  brain  and  spinal 
cord. 

The  lobulus  quadratus  (Q)  is  also  situated  upon  the  inner 
surface  of  the  cerebrum,  between  the  para-central  lobule  and 
the  lobulus  cuneus. 

The  occipital  lobule  (C)  is  triangular  in  form,  and  lies  pos- 
terior to  the  lobulus  quadratus  upon  the  inner  surface  of  the 
cerebrum. 

Certain  fissures  upon  the  inner  surface  of  the  cerebrum 
are  also  perceived,  whose  names  may  be  met  with  by  you  in 
the  descriptions  of  existing  lesions,  in  special  works  upon 
nervous  diseases,  and  which  are  therefore  enumerated.  They 
are  named  as  follows : 

The  calloso-marginal  fissure. 

The  internal  parieto-occipital  fissure. 

The  calcarine  fissure. 


CLINICAL  SUBDIVISIONS   OF  THE  BRAIN. 

In  studying  the  brain  from  the  standpoint  of  its  physiol- 
ogy and  clinical  interest,  an  advantage  is  gained  by  a  depart- 
ure from  the  subdivisions  of  the  encephalon  found  in  most 
of  our  standard  anatomical  treatises;  since  many  points, 
which  could  not  be  omitted  in  a  descriptive  treatise  without 
the  author  incurring  censure,  are  of  no  importance  to  the 
physiologist  or  pathologist,  in  our  present  ignorance  as  to  the 


w 


GENERAL  SUMMARY.  81 

functions  of  many  parts,  or  the  results  of  disease  when  con- 
fined exclusively  to  them.  I  am  inclined,  therefore,  to  adopt 
the  classification  of  Professor  Seguin,  used  some  years  ago 
in  a  course  of  lectures  delivered  upon  this  subject,'  since  it 
seems  to  possess  perspicuity  and  many  advantages  from  a 
clinical  standpoint.  I  quote  from  the  above  author  as  fol- 
ws : "" 

'Tor  our  purpose  I  make  the  following  subdivisions  of 
the  encephalon — a  semi-physiological  classification : ' 

^'1.  The  basis  cerehri,  including  all  the  parts  which  lie 
upon  the  base  of  the  skull,  but  more  especially  the  pons  Va- 
rolii, crura  cerebri,  their  attached  nerves,  and  the  optic  and 
olfactory  apparatuses. 

"2.  ThQ  great  basal  ganglia.,  i.  e.,  the  thalamus  opticus, 
nucleus  caudatus,  nucleus  lenticularis,  and  the  corpus  quadri- 
geminum. 

"3.  The  white  substance  of  the  hemispheres,  especially 
the  internal  capsule. 

I"  4.  The  cortex  cerebri. 
"5.  T^Q  cerebellum, 
"The  general  pathological  propositions  relative  to  these 
Tts  are  as  follows : 
"1.  Lesions  of  the  basis  cerebri^  especially  if  involving 
e  pons  Varolii  and  crura,  give  rise  to  the  following  symp- 
toms :  paralysis  (often  of  crossed  variety) ;  ansesthesia  in  the 
face  and  limbs  ;  impairment  of  equilibrium  ;  changes  within 
the  eyes ;  no  psychical  symptoms. 

"2.  Lesions  of  the  great  basal  ganglia  probably  produce 
,     no  symptoms  unless  by  encroaching  upon  the  internal  capsule 
i     which  passes  near  them.     An  exception  may  be  the  nucleus 
caudatus. 

''3.  Lesions  of  the  wTiite  center  of  the  heinispheres  pro- 
I  duce  no  symptoms  when  they  do  not  involve  the  parts  com- 
;     posing  the  internal  capsule ;  if  the  anterior  portion  of  this 

'  "N.Y.  Med.  Record,"  1878. 

2  lUd.,  February,  1878. 

3  The  italics  are  my  own. 


82  TEE  BRAIN. 

capsule  be  injured,  we  observe  paralysis,  if  i  ts  posterior  part, 
anaesthesia. 

''4.  Lesions  of  the  cortex  cerebri  produce,  when  located 
anteriorly,  psychical  sym^jtoms  ;  when  located  in  the  median 
regions,  paralysis  of  an  imperfect  kind,  and  when  situated 
posteriorly,  no  symptoms  at  all  (sensory  symptoms  in  animals). 

''5.  Lesions  of  the  cerebellum  produce  no  symptoms  ex- 
cept by  involving  adjacent  parts  containing  important  motor 
and  sensory  tracts,  thus  giving  rise  to  irregular  paralyses, 
changes  in  the  optic  apparatus,  symptoms  of  irritation  of  the 
vagus  nerve,  etc. 

^'  6.  Lesions  in  one  lateral  half  of  any  part  of  the  enceph- 
alon  produce  motor  and  sensory  symptoms  in  the  side  of  the 
body  opposite  to  the  lesion.  When  the  lesion  is  in  one  half 
of  the  basis  cerebri,  some  symptoms  (direct  symptoms)  are 
found  in  the  side  of  the  face  and  head  corresponding  to 
the  lesion,  others  in  the  opposite  half  of  the  body  (crossed 
paralysis). 

"7.  Lesions  in  the  median  line  cause  symptoms  to  appear 
in  both  sides  of  the  body. 

''  8.  Any  intra-cranial  lesion  which  acts  in  such  a  way  as  to 
increase  the  intra-cranial  pressure  may  produce  (in  addition 
to  other  symptoms)  the  condition  known  as  choked  disk,  or 
neuro-retinitis." 


SUMMARY  OF  THE  PHYSIOLOGY  OF  THE  CORTEX  AND  THE 
EFFECTS  OF  DISEASE  LOCATED  IN  THAT  PORTION  OF  THE 
CEREBRUM. 

From  the  statements  made  in  previous  pages,  we  may 
summarize  the  functions  of  the  cortex  (the  gray  matter  of 
the  cerebral  convolutions),  as  well  as  the  symptoms  which 
can  be  attributed  to  disease  confined  to  that  region,  as  fol- 
lows : 

1.  That,  contrary  to  old  statements,  the  cortex  is  capable 
of  artificial  stimulation ;  and  that  the  functions  of  certain 
areas  can  thus  be  determined  with  an  approach  to  accuracy. 


GENERAL  SUMMARY. 


83 


2.  That  a  well-defined    relation  exists   between  the  cor- 
tex and   certain  muscular    groups.      This    has   lately  been 


I  Fig.  25. — Side  view  of  the  brain  of  man  and  the  areas  of  the  cerebral  convolutions.     (After 

Ferrier.) 

^  1  (on  the  postero-parietal  [superior  parietal]  lobule),  advance  of  the  opposite  hind-limb 
as  in  walking ;  2,  3,  4  (around  the  upper  extremity  of  the  fissure  of  Rolando),  com- 
plex movements  of  the  opposite  leg  and  arm,  and  of  the  trunk,  as  in  swimming ; 
«,  6,  c,  d  (on  the  postero-parietal  [posterior  central]  convolution),  individual  and 
combined  movements  of  the  fingers  and  wrist  of  the  opposite  hand  :  prehensile  move- 
ments ;  5  (at  the  posterior  extremity  of  the  superior  frontal  convolution),  extension 
forward  of  the  opposite  arm  and  hand  ;  6  (on  the  upper  part  of  the  antero-parietal 
or  ascending  frontal  [anterior  central]  convolution),  supination  and  flexion  of  the 
opposite  forearm  ;  Y  (on  the  median  portion  of  the  same  convolution),  retraction  and 
elevation  of  the  opposite  angle  of  the  mouth  by  means  of  the  zygomatic  muscles  ;  8 
(lower  down  on  the  same  convolution),  elevation  of  the  ala  nasi  and  upper  lip  with 
depression  of  the  lower  lip,  on  the  opposite  side  ;  9,  10  (at  the  inferior  extremity  of 
the  same  convolution,  Broca's  convolution),  opening  of  the  mouth  with  9,  protrusion, 
and  10,  retraction  of  the  tongue — region  of  aphasia,  bilateral  action;  11  (between 
10  and  the  inferior  extremity  of  the  postero-parietal  convolution),  retraction  of  the 
opposite  angle  of  the  month,  the  head  turned  slightly  to  one  side  ;  12  (on  the  poste- 
rior portions  of  the  superior  and  middle  frontal  convolutions),  the  eyes  open  widely, 
the  pupils  dilate,  and  the  head  and  eyes  turn  toward  the  opposite  side  ;  13,  13  (on 
the  supra-marginal  lobule  and  angular  gyrus),  the  eyes  move  toward  the  opposite  side 
with  an  upward  13,  or  downward  13-  deviation  ;  the  pupils  generally  contracted  (cen- 
ter of  vision) ;  14  (of  the  infra-marginal,  or  superior  [first]  temporo-sphenoidal  con- 
volution), pricking  of  the  opposite  ear,  the  head  and  eyes  turn  to  the  opposite  side, 
and  the  pupils  dilate  largely  (center  of  hearing).  Ferrier,  moreover,  places  the  cen- 
ters of  taste  and  smell  at  the  extremity  of  the  temporo-sphenoidal  lobe,  and  that  of 
touch  in  the  gyrus  uncinatus  and  hippocampus  major. 


84  THE  BRAIX. 

confirmed  on  tlie  human  subject  by   Dr.   Amidon,   of  this 
city/ 

' "  Dr.  Amidon's  experiments  ^  in  ca-ebml  localization  are  based  on  the  following 
propositions:  1.  Marked  local  variations  in  the  temperature  of  the  cephalic  contents 
can  be  demonstrated  by  surface  thermometers.  2.  Cerebral  cortical  localization  is  now  so 
far  advanced  as  to  warrant  the  assertion  that  the  psycho-motor  centers  for  one  half  the 
body  occupy  a  certain  area  in  the  cerebral  cortex  of  the  opposite  hemisphere.  3.  Func 
tional  activity  of  an  organ  implies  increased  blood  supply  and  tissue  change,  and  conse- 
quent elevation  of  the  tanperature  of  that  organ.  4.  Willed  contraction  of  muscles  pre- 
supposes an  increased  activity  of  the  volitional  motor  center  of  those  muscles  in  the 
cerebral  cortex.  From  this  it  was  natural  to  make  the  deduction  that  voluntary  activity 
in  a  peripheral  part  would  cause  a  rise  of  temperature  in  the  psycho-motor  center  for  that 
part,  which  might  be  indicated  by  external  cerebral  thermometers. 

"  Scguin's  self-registering  surface  thermometers  were  used,  numbers  of  which  were 
applied  to  the  surface  to  be  tested  by  passing  them  through  holes  in  rubber  straps 
secured  to  the  head  by  buckles.  The  desirable  points  in  the  subject  experimented  on 
are,  a  well-shaped  head,  thin  hair,  well-developed  and  trained  muscles,  power  of  facial 
expression,  especially  of  unilateral  facial  movements  and  the  ability  to  contract  individual 
muscles,  and  moderate  intelligence.  A  man  is  preferable  to  a  woman,  and  a  Eurojjeaii 
to  an  African.  The  mode  of  performing  and  recording  experiments  and  the  liabilities  b 
error  are  all  fully  described,  and  the  following  results  are  given. 

"The  part  of  the  brain  underlying  the  trapezius  area  is  thus  seen  to  be  the  anterior 
part  of  the  first  frontal  convolution.  Farther  back  on  the  same  comes  the  deltoid,  and 
farther  still  the  biceps  area,  while  that  of  the  triceps  probably  overlaps  to  a  slight  degree 
the  fissure  of  Rolando.  The  area  for  the  scaleni,  etc.,  will  fall  on  the  second  frontal 
convolution,  in  front  of  its  middle ;  that  for  the  deep  extensors  of  the  neck,  on  the 
second  frontal  convolution,  near  its  middle.  The  pectoralis  area  will  fall  on  the  middle 
of  the  second  frontal  convolution,  slightly  overlapping  the  superior  frontal  sulcus.  The 
area  for  the  latissimus  dorsi  occupies  a  similar  position  farther  back.  The  point  of 
junction  of  the  superior  and  ascending  frontal  is  occupied  by  the  hand  and  finger  flexors, . 
while  lower  on  the  ascending  frontal  lies  the  area  for  the  elevators  of  the  angle  of  thr 
mouth,  and  lower  still,  that  for  the  orbicularis  oris,  in  front  of  and  above  which  is  tin 
area  for  the  tongue  and  the  hyoids,  which  lies  on  the  third  frontal  convolution.  At  the 
base  of  the  ascending  parietal  convolution,  but  reaching  a  slight  distance  across  the 
fissure  of  Rolando,  lies  the  platysma  area ;  higher,  the  area  for  the  orbicularis  palpe- 
brarum, and  higher  still,  lying  partly  on  the  ascending  parietal,  and  partly  on  the  ascend- 
ing frontal  convolutions,  is  the  area  for  the  extensors  of  the  hand  and  fingers.  The  ante- 
rior part  of  the  superior  parietal  lobule  holds  the  anterior  tibial  area,  behind  which  lies  that 
of  the  calf  of  the  leg.  On  the  posterior  part  of  the  superior  parietal  lobule,  but  falhng 
chiefly  on  the  first  and  second  occipital  gyri,  is  found  the  area  for  the  quadriceps  extensor 
femoris,  while  on  the  third  occipital  gyrus  and  the  posterior  part  of  the  inferior  middle 
temporal  lobule  will  fall  the  area  for  the  abdominal  muscles.  On  the  posterior  parts  of 
the  angular  gyrus  and  middle  temporal  lobule  will  fall  the  psoas  and  iliacus  area.  The 
rather  indefinite  area  marked  out  for  the  erector  spince  overlies  about  equally  the  pos- 
terior part  of  the  upper  and  of  the  middle  temporal  lobules,  while  higher  up,  over  the 
contiguous  portions  of  the  angular  and  supra-marginal  gyri  and  the  superior  temporal 
lobule,  is  the  area  for  the  flexors  of  the  leg  on  the  thigh.  On  the  upper  part  of  the 
supra-marginal  gyrus  will  fall  t!ie  area  set  apart  for  ocular  movements.  This  transfer- 
ence of  the  motor  areas  from  the  scalp  to  the  brain  leaves  but  little  of  the  cerebral  con- 
vexity uncovered,  viz.,  the  anterior  half  of  the  temporo-sphenoidal  lobe  and  the  extreme 


Prize  Essay  of  1880,  "Archives  of  Medicine,"  April,  1880. 


GENERAL  SUMMARY. 


85 


3.  That  the  excitable  region  of  the  cortex,  where  motor 
effects  are  chiefly  jjroduced,  may  be  stated  to  be  localized  in 
the  following  parts,  if  we  accept  the  results  obtained  by  Ter- 
rier :  The  ascending  frontal  convolution  ;  the  base  of  the  first 
frontal    convolution ;    the   second  frontal    convolution ;    the 
third  frontal  convolution ;  the  ascending  parietal  convolu- 
ion  ;  the  first  parietal  convolution  ;  and  the  para-central  lob- 
le.     Now,  let  us  see  what  centers  pertain  to  each  of  these 
mvolutions. 

e  center  for  movements  of  tlie  lips  and  tongue  (the  true 
speech  center)  lies  at  the  base  of  the  tJiird  frontal  convo- 
lution, near  the  fissure  of  Sylvius.     (See  9,  10,  on  Fig.  25.) 
pon  the  first  and  second  frontal  convolutions,  you  will  find 
a  center  (see  12,  on  Fig.  25)  :  (1)  For  lateral  movements 

^of  the  Tiead ;  (2)  for  elevation  of  the  eyelids ;  and  (3) 
for  dilatation  of  the  pupil. 
e  ascending  frontal  convolution  presents,  from  below  up- 
ward, the  following  centers :  For  elevation  and  depres- 
sion of  the  corners  of  the  mouth  (8  and  7) ;  for  move- 
ments of  the  forearm  and  the  hand  (6) ;  for  extension 
and  the  forward  movement  of  the  hand  and  the  arm  (5) ; 
centers  for  complex  movements  of  the  arms  and  legs^ 
w^hen  acting  together  (2,  3,  and  4). 
The  ascending  parietal  convolution  presents,  from  above 
downward,  four  centers  for  complex  movements  of  the 
hand  and  wrist  {a,  b,  c,  d ),  such  as  the  use  of  individual 
fingers,  prehensile  movements,  etc.  At  its  most  superior 
portion,  the  centers  (2,  3,  and  4),  which  control  the  alter- 
nating movements  of  the  arm  and  leg,  as  in  the  act  of 
swimming,  seem  to  overlap  the  ascending  parietal  convo- 
lution ;  but  they  are  not  definitely  placed. 
The  superior  parietal  convolution  presents  the  center  which 
presides  over  the  movements  of  the  leg  and  foot,  as  in  the 
act  of  walking. 

anterior  frontal  region.    Tliese  areas  are  held  to  be  the  outward  representation  of  psycho- 
motor centers  in  the  cerebral  cortex."   (Report  in  "Xew  York  Med.  Jour.,"  October,  1880.) 


86  TEE  BRAm. 

The  para-central  lobule^  when  diseased  or  excised,  seems  to 
exert,  through  some  influences,  a  gradually  extending 
process  of  secondary  degeneration  of  the  spinal  cord. 

4.  The  sensory  region  of  the  cortex  is  confined  to  the  parie- 
tal, temporal,  and  occipital  lobes  of  the  cerebrum.  In  it  cer- 
tain centers  have  been  definitely  located  by  Ferrier,  which  are 
not,  as  yet,  accepted  as  fully  proven,  but  which  are  consid- 
ered as  being  rather  supported  than  confuted  by  clinical  and 
physiological  evidence. 

The  angular  gyrus  is  said  by  this  author  to  present  the  cen- 
ters for  vision  (13,  13),  while  movements  of  the  eyes  also 
are  produced  when  these  regions  are  stimulated. ' 

The  superior  teniporo-spTienoidal  convolution  is  also  said  to 
present  the  centers  of  hearing  (14,  14,  14),  while  the  head 
and  eyes  are  caused  to  move  toward  the  opposite  side  and 
the  pupils  to  dilate  largely. 

5.  The  collection  of  reported  cases  of  tumors,  clots,  soft- 
enings, pressure  effects  (from  exostoses,  meningeal  exuda- 
tions, or  thickenings,  etc.),  seems  to  confirm,  to  a  greater  or 
less  extent,  the  effects  of  physiological  experiment  or  faradi- 
zation, and  that  the  following  general  statements  as  to  the 
results  of  lesions  of  the  cortex  can  be  safely  used  as  possess- 
ing practical  value  at  the  bedside. 

(a)  When  t\iQ  faculty  of  speech  is  affected  to  any  extent,  or 
the  symptoms  of  amnesic  aphasia  exist,  it  is  safe  to  con- 
clude that  the  lesion  involves  one  of  three  situations,  viz.  : 
the  anterior  convolutions  of  the  island  of  Reil,  the  base 
of  the  third  frontal  convolution,  or  the  white  substance 
lying  between  the  third  frontal  convolution  and  the  base 
of  the  cerebrum. '  The  lesion,  being  most  frequently  met 
with  upon  the  left  side  of  the  brain,  will  usually  be  asso- 

'  Experiments  of  Ferrier,  Yeo,  Dalton,  and  others. 
»  E.  C.  Seguin,  "  Med.  Record,"  1878. 


GENERAL  SUMMARY. 


87     ' 


Fig.  26 — Upper  viae  of  the  brain  of  man  ayid  the  situation  of  areas  of  the  cerebral  con- 
volutions. (After  Ferrier.) 
(on  the  postero-parietal  [superior  parietal]  lobule),  advance  of  the  opposite  hind- 
limb  as  in  walking ;  2,  y,  4  (around  the  upper  extremity  of  the  fissure  of  Rolando), 
complex  movements  of  the  opposite  leg  and  arm,  and  of  the  trunk,  as  in  swim- 
ming ;  «,  6,  c,  d  (on  the  postero-parietal  [posterior  central]  convolution),  indi- 
vidual and  combined  movements  of  the  fingers  and  wrist  of  the  opposite  hand ;  pre- 
hensile movements  ;  5  (at  the  posterior  extremity  of  the  superior  frontal  convolu- 
tion), extension  forward  of  the  opposite  arm  and  hand  ;  6  (on  the  upper  part  of 
the  antero-parietal  or  ascending  frontal  [anterior  central]  convolution),  supination 
and  flexion  of  the  opposite  forearm ;  7  (on  the  median  portion  of  the  same  con- 
volution), retraction  and  elevation  of  the  opposite  angle  of  the  mouth  by  means  of 
the  zygomatic  muscles ;  8  (lower  down  on  the  same  convolution),  elevation  of 
the  ala  nasi  and  upper  lip  with  depression  of  the  lower  lip,  on  the  opposite  side ;  9, 
10  (at  the  inferior  extremity  of  the  same  convolution,  Broca's  convolution),  open- 
ing of  the  mouth  with  9,  protrusion,  and  10,  retraction  of  the  tongue — region  of 
aphasia,  bilateral  action;  11  (between  10  and  the  inferior  extremity  of  the  pos- 
tero-parietal convolution),  retraction  of  the  opposite  angle  of  the  mouth,  the  head 
turned  slightly  to  one  side  ;  12  (on  the  posterior  portions  of  the  superior  and  mid- 
dle frontal  convolutions),  the  eyes  open  widely,  the  pupils  dilate,  and  the  head  and 
eyes  turn  toward  the  opposite  side  ;  13,  13  (on  the  supra-marginal  lobule  and  an- 
gular gyrus),  the  eyes  move  toward  the  opposite  side  with  an  upward  13,  or  down- 
ward 13"  deviation — the  pupils  generally  contracted  (center  of  vision);  14  (of 
the  infra-marginal,  or  superior  [first]  temporo-sphenoidal  convolution),  pricking  of 
the  opposite  ear,  the  head  and  eyes  turn  to  the  opposite  side,  and  the  pupils  dilate 
largely  (center  of  hearing),  Ferrier,  moreover,  places  the  centers  of  taste  and  smell 
at  the  extremity  of  the  temporo-sphenoidal  lobe,  and  that  of  touch  in  the  gyrus  un- 
cinatus  and  hippocampus  major. 


88  THE  BRAm. 

ciated  with  some  form  of  paralysis  affecting  the  right 
side  of  the  body ;  but  the  faculty  of  speech  may  be  af- 
fected by  lesions  of  the  right  side  as  well  as  those  of  the 
left  side. 

(b)  Paralysis  of  motion  affecting  the  upper  extremity^  either 

entirely  or  to  a  greater  extent  than  other  parts  involved, ' 
suggests  a  lesion  which  is  situated  on  the  side  opposite  to 
the  paralysis ;  and  either  confined  to,  or  involving,  the 
ascending  convolutions  of  the  frontal  or  parietal  lobes. 

(c)  When  the  facial  muscles  are  prominently  affected,  I  am 

inclined  to  think  the  lesion  may  be  located  in  the  frontal 
lobe,  anterior  to  or  in  the  vicinity  of  the  pre-central  fis- 
sure or  sulcus. "" 

(d)  When  the  muscles  of  the  leg '  are  exclusively  affected  (and 
the  probability  of  spinal  lesions  involving  only  the  lateral 
half  of  the  spinal  cord  can  be  excluded),  or  when  the  leg 
muscles,  in  an  attack  of  hemiplegia  of  clear  cranial  ori- 
gin, show  special  impairment,  the  lesion  can  be  probably 
placed  at  the  upper  end  of  the  fissure  of  Rolando^  affect- 
ing the  ascending  convolutions  of  the  frontal  or  parietal 
lobes. 

{e)  That  lesions  of  the  sensoi^y  area  of  the  cerebral  cortex  are 
not  understood  in  their  clinical  aspects^  since  little  op- 
portunity has  been  afforded  for  the  pathological  study  of 
this  type  of  cases. 

(/)  That  all  of  the  symptoms  produced  by  lesions  of  the  cor- 
tex may  be  the  result  either  of  actual  destruction  of  the 
nerve  tissue  of  the  cortex,  or  evidences  of  irritation  of 
the  cortex ;  and  that  the  symptoms  will  differ  in  the 
two  cases,  so  as  to  often  assist  the  diagnostician. 

{g)  That  lesions  of  the  cortex,  if  outside  of  the  motor  area^ 
will  produce  no  symptoms,  unless  they  involve  the  dura 
mater ;  in  which  case,   the  diseased  condition  may  be 

^  See  the  peculiar  types  of  brachial  monoplegia,  as  described  on  pages  45  and  46  of 
this  volume. 

'  It  may  not  be  confined  alone  to  this  region,  since  the  various  forms  of  brachial 
monoplegia  are  often  associated  with  facial  paralysis. 

*  See  the  types  of  crural  monoplegia,  described  on  pages  40  and  42  of  this  yolume. 

1 


GENERAL  SUMMARY.  S9 

manifested  by  convulsions^  and,  possibly,  by  headache. 
These  convulsions,  and  the  headache  which  may  be  pro- 
duced, are  respective  evidences  of  irritation  of  some  por- 
tion of  the  motor  area  of  the  cortex,  or  of  adjoining  sen- 
sory areas. 
(/)  That  the  symptoms  which  prominently  indicate  irritation 
of  the  cortex  are  convulsions^  which  are  oiten  followed  hy 

»  paralysis.  This  paralysis  may  be  either  of  the  transient 
or  permanent  variety,  although  the  former  is  the  more 
common.  The  groups  of  muscles  which  are  prominently 
affected  in  the  convulsive  attacks  may  afford  the  physi- 
cian a  guide  to  the  seat  of  the  irritation,  since  the  same 
centers  are  probably  affected,  as  if  the  corresponding 
muscles  w^ere  paralyzed,  rather  than  convulsed. 
{j)  The  destructive  lesions  of  the  gray  matter  of  the  cerebral 

I  convolutions,  if  limited  to  the  motor  area,  produce  pe- 
ripheral paralysis  of  the  parts  governed  by  the  centers 
which  are  involved,  but  on  the  side  of  the  body  opposite 
to  the  situation  of  the  seat  of  disease.  Thus  embolism, 
by  plugging  the  middle  cerebral  artery,  shuts  off  the 
blood  supply  to  the  center  of  Broca,  and  aphasia  will 
usually  be  produced  ;  with  an  accompanying  hemiplegia 
of  the  side  opposite  to  the  embolus,  in  case  the  blood 
supply  is  impaired  to  other  parts  of  the  motor  area.  A 
destructive  lesion  of  the  motor  region,  if  not  due  to  em- 
bolism, is  liable  to  produce  hemiplegia,  without  aphasia, 
on  the  opposite  side  to  the  seat  of  disease  ;  but  it  exists 
to  a  greater  or  less  extent  when  the  motor  area  of  the 
cortex  is  affected  in  any  part. 
{k)  When  the  paralyzed  muscles  become  rigid^  after  an  at- 
tack of  hemiplegia,  from  destructive  lesions  of  the  motor 
area  of  the  cortex,  it  may  be  considered  as  an  evidence  of 
a  secondary  degeneration  of  the  nerve  fibers,  which  is 
progressing  downward  along  the  spinal  cord.  This  is 
prominently  developed  w^hen  the  para- central  lobule  is 
the  seat  of  disease,  but  it  exists,  to  a  greater  or  less  extent, 
when  the  motor  area  of  the  cortex  is  affected  in  any  part. 


90  THE  BE  A  IK 

{T)  In  those  cases  where  the  lesions  are  diffused  over  a  large 
surface  of  the  cortex  (as  in  the  exudation  of  acute  menin- 
gitis, suppuration  between  the  bone  and  the  dura  mater, 
etc.),  delirium,  convulsions,  and  local  pain,  are  often  pres- 
ent, and  may  properly  be  regarded  as  evidences  of  the 
excessive  irritation  which  exists  in  consequence  of  the 
pressure  and  hypersemia.  Coma  and  paralysis  may  fol- 
low ;  in  which  case  they  are  to  be  attributed,  either  to  the 
local  anaemia  produced  by  the  pressure  (thus  causing  im- 
pairment of  nutrition  to  the  subjacent  cortex),  or  to  circu- 
latory changes  and  increased  tension  of  the  entire  brain. 

{m)  The  affection  called  ''diffuse  meningo-encephalitis "  or 
the  ''general  paralysis  of  the  insane"  is  so  commonly 
met  with,  and  affords  such  striking  evidences  of  the  effects 
of  general  pressure  upon  and  irritation  of  the  cerebral 
cortex,  that  its  symptoms  have  to  the  neurologist  more 
than  a  clinical  interest.  From  a  careful  study  of  such 
cases,  we  learn  that  the  symptoms  first  manifested  are 
contractions  of  special  fibers  in  the  muscles  of  the  face, 
tongue,  and  limbs,  and  that  the  speech  becomes  tremu- 
lous and  the  articulation  spasmodic.  Later  on,  acute 
delirium  and  impairment  of  memory  and  judgment  ap- 
pear, and  a  state  of  the  muscles  of  the  limbs  develoj)s 
which  may  be  one  either  of  semi-paralysis  or  of  semi- 
ataxia.  In  the  final  stages,  the  mental  faculties  become 
abolished ;  a  state  of  insanity,  characterized  by  periods  of 
delirium,  is  produced  ;  and  the  patient  dies  without  any 
apparent  changes  in  the  ordinary  organic  functions  of 
the  body. 

I  would  repeat,  that  a  person  exhibiting  tremors  of 
the  facial  muscles,  of  the  tongue,  and  hand,  a  vibratory 
and  slurred  speech,  angular  or  tremulous  handwriting, 
and  irregular,  small  pupils,  should  be  suspected  of  having 
chronic  peri-encephalitis  or  paralytic  dementia.  The  ad- 
dition of  gradual  failure  of  mind — true  dementia — makes 
the  diagnosis  certain.  In  case  there  should  be  added  to 
these  above  named  symptoms  exalted  notions,  with  ma- 


p 


GENERAL  SUMMARY.  91 

niacal  attacks  and  epileptiform  seizures,  the  case  deserves 
the  name  of  general  paresis,  and  as  such  the  form  is  more 
usually  seen  and  studied  by  asylum  physicians. 

6.  The  physiology  of  the  great  ganglia  of  the  cerebrum  is 
far  from  being  satisfactorily  determined,  since  the  experi- 
ments of  different  observers  apparently  prove  most  glaring 
contradictions.  It  is,  however,  probable  that  the  two  subdi- 
visions of  the  corpus  striatum  (the  caudate  and  the  lenticu- 

r  nuclei)  have  motor  functions  of  a  character  which  are  not 
yet  positively  decided,  while  the  attributes  of  the  optic  thala- 
mus are  still  involved  in  obscurity.' 

7.  It  can  safely  be  considered  as  proven  that  the  corpora 
quadrigemina  (the  nates  and  testes)  are,  in  some  way,  con- 
cerned in  the  special  sense  of  vision,  and  belong  to  the  optic 
apparatus,  although  the  motions  of  the  eyeball  seem  to  be 

ore  directly  influenced  than  vision  itself.  For  the  experi- 
ents  which  seem  to  prove  this,  the  reader  is  referred  to 
ge  58  and  59  of  this  volume. 

8.  The  internal  capsule  of  the  cerebrum  seems  to  be  one 
f  the  most  important  regions  of  the  brain,  from  a  clinical 

standx)oint,  since  the  slightest  pressure  upon  it  produces 
ptoms  which  vary  with  the  portion  pressed  upon,  and 
since  a  secondary  degeneration^''  which  descends  along  the 
nerve  fibers  of  the  crus,  pons,  medulla,  and  spinal  cord,  is  in- 
evitably the  result  of  disease  of  this  portion  of  the  cerebrum. 
If  the  anterior  two  thirds  of  the  internal  capsule  be  the  seat 
of  pressure  or  disease,  hemiplegia  of  the  opposite  side  re- 
sults ;  if  the  posterior  third  be  affected,  a  condition  of  ances- 
thesia  of  the  opposite  side  is  produced.  Choreic  movements^ 
which  vary  in  degree  and  type,  and  which  may  appear  as 
athetosis,  ataxia,  true  chorea,  or  tremor,  are  strongly  diag- 
nostic of  lesion  of  the  internal  capsule,  provided  they  follow 
an  attack  of  hemiplegia  or  hemi-ansesthesia. 

*  To  what  extent  this  ganglion  presides  over  or  influences  sensory  perceptions  must 
be  considered  unsettled.  For  opinions  on  the  subject,  the  reader  is  referred  to  page  57 
of  this  volume. 

2  For  the  eifects  of  this  descending  t3;pe  of  secondary  degeneration  of  nerve  tissue,  see 
page  44  of  this  voluinp. 


i     Stan 


92  THE  BRAIN. 

9.  The  parts  adjoining  the  internal  capsule  (the  caudate 
nucleus,  the  lenticular  nucleus,  the  white  center  of  the  frontal 
lobe,  and  the  optic  thalamus),  if  the  seat  of  hsemorrhage,  tu- 
mors, or  other  lesions  which  are  capable  of  causing  pressure 
upon  it,  may  produce  symptoms  similar  to  those  of  disease  of 
the  internal  capsule  itself. 

10.  When  the  central  portions  of  the  cerebral  hemispheres 
are  the  seat  of  some  type  of  disease  which  has  been  suddenly 
developed,  as  in  hsemorrhage,  acute  softening,  etc.,  symptoms 
referable  to  the  optic  apparatus  are  usually  present,  in  addi- 
tion to  the  other  symptoms  which  have  been  given  above. 
Thus  the  eyes  are  often  turned  away  from  the  paralyzed  side, 
and,  therefore,  toward  the  seat  of  the  lesion ;  the  head  also  is 
usually  similarly  turned  ;  and,  in  case  the  injury  done  to  the 
brain  is  severe  or  extensive,  a  very  marked  rise  in  the  surface 
temperature  of  the  body  will  be  observed. 

11.  AVhen  the  pressure  upon  the  central  portions  of  the 
cerebral  hemispheres  is  gradual^  as  in  the  case  of  growing 
tumors,  we  have  developed  certain  special  signs,  which  de- 
pend upon  the  situation  of  the  tumor  and  the  line  of  its  great- 
est pressure  ;  but  we  are  also  liable  to  have  evidences  develoj) 
in  the  eye,  which  are  called  those  of  "neuro-retinitis,"  and 
may  result  in  the  condition  known  by  ophthalmologists  as 
the  *' choked  disk." 


THE  CRANIAL  I^ERYES. 

lEIR  ANATOMY,  PHYSIOLOGY,  AND  CLINICAL  VALUE. 


THE   OEANIAL  KEEYES. 


The  nerves  which  arise  from  the  brain  are  arranged  as ' 
twelve  pairs,  which  from  before  backward  are  called  the  ol- 
factory, optic,  motor  oculi,  trochlearis,  trigemini,  abducens, 
facial,  auditory,  glosso-pharyngeal,  pnenmogastric,  spinal  ac- 
cessory, and  hypo-glossal.  All  of  these,  excepting  the  ninth, 
tenth,  and  eleventh  pairs,  are  confined  in  their  distribution  to 
the  head;  while  the  other  three  have  a  distribution  to  the 
structures  of  the  neck  and  trunk. 

THE  OLFACTORY   XERYE. 

The  first  cranial  nerve  or  nerve  of  smell  consists  (1)  of 
three  roots  ;  (2)  an  olfactory  process  ;  (3)  a  bulb  ;  and  (4)  ter- 
minal branches,  which  are  distributed  to  the  cavities  of  the 
nose. 

The  three  roots  are  called  the  external,  middle,  and  in- 
ternal. 

The  external  root  arises  apparently  from  the  posterior  bor- 
der of  the  fissure  of  Sylvius,  and  is  said  to  be  traceable  to  the 
corpus  striatum,  the  anterior  commissure,  the  optic  thalamus, 
and  the  island  of  Reil.  The  internal  or  short  root  is  said  by 
Foville  to  be  connected  with  the  longitudinal  fibers  of  the 
gyrus  fornicatus.  The  middle  or  gray  root  arises  from  a 
pyramidal  mass  of  gray  matter,  the  caruncula  mammillaris. 

1  Willis  has  divided  the  cranial  nerves  into  nine  pairs,  grouping  the  seventh  and 
eighth  nerves  as  one  pair,  and  the  ninth,  tenth,  and  eleventh  as  one  pair. 


96 


THE  CRANIAL  NERVES. 


All  three  of  the  roots  join  to  form  a  band,  which  is  prismoidal 
in  form  (the  olfactory  process  or  tract),  which  passes  forward 


Fig.  27. — Roots  of  the  cranial  nerves.     (Hirschfeld.) 
I.  First  pair;  olfactory. 
II.  Second  pair ;  optic. 

III.  Third  pair ;  motor  oculi  communis. 

IV.  Fourth  pair;  patheticus. 

V.  Fifth  pair ;  nerve  of  mastication  and  trifacial. 
VI.  Sixth  pair;  motor  oculi  externus. 

IX.  Glosso-pharyngeal,  \ 
X.  Pneumogastric,        >•  Eighth  pair. 

XI.  Spinal  accessory,      ) 
XII.  Ninth  pair;  sublingual. 
The  numbers  1  to  15  refer  to  branches  which  will  be  described  hereafter. 


along  the  floor  of  the  brain  in  a  deep  sulcus  till  it  expands 
into  the  terminal  enlargement,  known  as  the  "  olfactory  bulb," 
or  *^  ganglion."  This  terminal  enlargement  lies  upon  the 
upp'^r  surface  of  the  cribriform  plate  of  the  ethmoid  bone, 
through  the  numerous  foramina  of  which  its  branches  escape, 
as  small,  thread-like  filaments ;  which  subsequently  form  a 
plexus  upon  the  surface  of  the  Schn^iderian,  er  pituitary^ 
membrane  of  the  nose. 


STRUCTURE  OF  OLFACTORY  FILAMENTS. 


97 


Fig.  28. —  Olfactory  ganglion  and  nerves.  (Ilirschfeld.) 
1,  olfactory  ganglion  and  nerves  ;  2,  branch  of  the  nasal  nerve;  3,  sphcno-palatine  gan- 
glion ;  4,  7,  branches  of  the  great  palatine  nerve ;  5,  posterior  palatine  nerve ;  6,  mid- 
dle palatine  nerve;  8,  9,  branches  from  the  spheno-palatine  ganglion;  10,11,  12, 
Vidian  nerve  and  its  branches;  13,  external  carotid  branch  from  the  superior  cervical 
ganglion. 

The  filaments  of  the  olfactory  nerve  are  described  by 
^lessrs.  Todd  and  Bowman^  as  differing  in  their  structure 
from  the  ordinary  filaments  found 
ill  the  other  cranial  nerves,  in  that 
they  contain  no  white  substance  of 
Schwann,  and  are  nucleated  and  fine- 
ly granular  in  texture.  This  absence 
of  the  white  substance,  found  in 
other  nerves,  renders  it  difficult  to 
trace  their  course  in  the  Schneiderian 
membrane ;  which  difficulty  is  still 
further  enhanced  by  the  existing  nu- 
clei, which  resemble  those  of  the  tis- 
sues through  which  they  pass. 

The  limit  of  distribution  of  the 
olfactory  nerves  seems  to  be  confined 
to  the  superior  three  fourths  of  the 
septum  of  the  nose,  the  superior  tur- 
l)inated  bone,  the  upper  half  of  the 
middle  turbinated  bone,  and  the  roof 

1  "Physiological  Anatomy 


Fig.  29. —  Terminal  filaments  of 
the  olfactory  nerves  ;  magnified 
30  diameters.     (Kolliker.) 

1,  from  the  frog— a,  epithelial 
cells  of  the  olfactory  region ; 
6,  olfactory  colls.  2.  Small 
branch  of  the  olfactory  nerve 
of  the  frog,  separating  at  one 
end  into  a  brush  of  varicose 
fibrils.  3.  Olfactory  cell  of 
the  sheep. 


98  THE  CRANIAL  NERVES. 

of  the  nasal  cavities ;  all  of  which  seems  to  be  defined  by  a 
brown-colored  tesselated  epithelium/ 

Odorous  particles,  present  in  the  inspired  air,  as  they  pass 
through  the  lower  chambers  of  the  nares,  are  diffused  intr) 
the  upper  nasal  chambers,  and,  falling  upon  the  olfactory 
epithelium,"  produce  sensory  impulses  which  are  transmitted 
to  the  brain  and  give  rise  to  the  sensations  of  smell. 

Forced  inspiration,  or  sniffing,  increases  the  upward  dif- 
fusion of  inspired  air,  and  thus  a  more  complete  contact  of 
the  odorous  particles  is  insured. 

It  seems  that,  for  the  development  of  smell,  the  odorous 
particles  must  be  transmitted  to  the  nasal  mucous  membrane 
in  a  gaseous  medium,  as  the  simultaneous  contact  of  fluids 
destroys  all  appreciation  of  odor.' 

Animals  with  a  very  acute  sense  of  smell  have  a  modified 
arrangement  of  the  turbinated  bones,  to  afford  a  larger  ex- 
panse of  surface  than  exists  in  man. 

It  has  been  asserted  by  some  physiologists  that  the  olfac- 
tory nerve  is  not  the  only  nerve  of  smell,  and  Magendie 
claimed  that  animals  could  perceive  the  odor  of  some  sub- 
stances after  the  olfactory  bulbs  had  been  removed.  He  used 
ammonia,  however,  as  a  test  in  his  experiments,  which  is 
hardly  a  test  of  smell,  as  it  is  a  powerful  stimulant  to  the  fifth 
nerve. 

Bernard'  reports  cases  of  absence  of  the  olfactory  bulb> 
in  man,  where  smell  existed  during  life.  Prevost,*  however. 
claims  that  section  of  the  olfactory  bulbs  entirely  destroys  the 
sense  of  smell.  Injury  to  the  JlftJi  nerve  may  also  destroy 
smell,  even  where  the  olfactory  nerve  remains  intact ;  but  this 
effect  is  hardly  a  proof  that  the  nerve  is  in  any  way  related  to 
that  special  sense,  since  the  effect  is  probably  due  to  an  altered 
condition  of  tlie  nasal  mucous  merribrane^  which  prevents  its 
performing  its  natural  function.  The  loss  of  smell  may, 
therefore,  be  of  some  diagnostic  value,  if  associated  with  other 
symptoms  referable  to  impairment  of  the  fifth  cranial  nerve. 

»  Max  Schultze.  »  Mich.  Foster,  "  Tcxt-Book  of  Physiology." 

■  "  Syst.  ncrv.,"  vol.  ii.    .  *  "  Archives  dc  sci.  phys.  et  nat.,"  1871. 


i 


TEE  PERCEPTIONS  OF  ODOR. 


It  seems  necessary,  in  all  animals  which  live  in  the  air, 
that  all  odorous  materials  must  enter  the  nostril  to  be  per- 
ceived, and,  furthermore,  that  the  membrane  of  the  nose  must 
be  in  a  proper  condition  of  moisture ;  hence,  by  breathing 
through  the  mouth,  the  most  disagreeable  of  odors  may  usu- 
ally be  unperceived,  and  the  blunted  sensibility  of  the  power 
of  smell,  which  occurs  in  catarrh,  may  plausibly  be  explained 
as  the  result  of  a  deficient  secretion  in  the  early  stage  of  the 
attack,  and  of  excessive  secretion  later  on  in  the  disease. 
The  curious  effects  of  section  or  injury  of  the  fifth  cranial 
nerve  ujjon  the  sense  of  smell  may  justly  be  attributed  to  the 
alteration  in  the  amount  of  secretion  of  the  lining  membrane 
of  the  nose,  since  this  nerve  exerts  a  marked  influence  upon 
the  secretions  of  the  tissues  supplied  by  it. 


ymvrr  wvviiir 


Fig.  30. — Internal  branches  of  the  olfadori^  nerve.  (After  Sappcy.) 
1,  internal  branches  of  the  olfactory  bulb,  ramifying  in  the  mucous  membrane  covering 
the  septum  of  the  nasal  fossae ;  2,  internal  branch  of  the  ethmoidal  division  of  the 
nasal  nerve;  3,  naso-palatine  nerves;  4,  5,  6,  cavernous  plexus;  7,  superior  or 
ascending  branches  of  this  plexus ;  8,  internal  carotid  branch  from  the  superior  cer- 
vical gandion;  9,  9,  filaments  connecting  this  branch  with  the  external  carotid 
branch  ;  lo,  origin  of  this  branch  ;  11,  ganglion  of  the  glosso-pharyngeal ;  12,  jugu- 
lar ganglion  of  the  pneumogastric ;  13,  anastomotic  filaments  extending  from  the 
sympathetic  to  the  two  preceding  nerves  ;  14,  anastomosis  of  the  spinal  accessory 
with  the  pneumogastric;  15,  filament  connecting  the  sympathetic  with  the  hypo- 
glossal ;  I,  olfactorv ;  II,  optic ;  III,  motor  oculi ;  IV,  patheticus  -^  V,  trigeminus  ; 
VI,  abducens;  VII,'  facial;:  yjH.;  f?«dv^ory^JX^  ^glp^so-^par^geaf;,  X,  pneumogas- 
tric ;  XI,  spinal  accessorij^  i^-^^i  Kypo^glos'^al;  ?        '. ,-,-";;,,'  ' 


act  of  sn^j^nfi,\^f  "^^^^  ^^VforcMo^^^^     of  air  is 
through  the^hoiiriisVrsVftenane&ft^on"^  of 


The 
■driven  throng] 
INature  to  get  rid  of  some  irritating  substance  ;   and  thus, 


100  THE  CRANIAL  NERVES. 

through  the  agency  of  the  fifth  nerve,  is  the  nose  made  the 
portal  of  the  respiratory  apparatus,  where  cognizance  of  the 
quality  of  the  air  breathed  is  constantly  taken,  and  where  all 
foreign  or  injurious  matters  are  at  once  detected,  and  often 
expelled. 

A  marked  peculiarity  of  the  olfactory  nerve  is  shown  by 
the  fact  that  no  form  of  irritation  of  its  fibers  excites  reflex 
muscular  action  through  other  nerves  ;  *  neither  is  it  capable 
of  the  sensation  of  pain,  since  section  of  the  nerve,  or  even  the 
destruction  of  the  olfactory  ganglia,  seems  to  create  no  special 
distress  in  animals,  and  the  nose  retains  its  normal  sensitive- 
ness until  the  fifth  nerve  is  also  divided. 

The  olfactory  nerve,  however,  may  be  the  source  of  another 
variety  of  marked  reflex  action.  Many  cases  are  recorded 
where  fainting  and  vomiting  have  been  produced  by  certain 
odors ;  while,  for  some  unexplained  reason,  mental  associa- 
tions cluster  around  sensations  of  smell  more  strongly  than 
any  other  form  of  impression  received  from  without.'* 

The  importance  of  the  sense  of  smell  among  many  of  the 
lower  animals,  in  guiding  them  to  their  food,  or  in  giving 
them  warning  of  danger,  and  also  in  exciting  the  sexual  feel- 
ings, is  well  known.  Among  the  savage  tribes,  whose  senses 
are  more  cultivated  than  those  of  civilized  nations,  the  scent 
is  almost  as  acute  as  in  the  lower  mammalia.  It  is  asserted  by 
Humboldt  that  the  Peruvian  Indians,  in  the  middle  of  the 
night,  can  thus  distinguish  the  different  races,  whether  Euro- 
pean, American,  Indian,  or  Negro. 

The  agreeable  or  disagreeable  character  assigned  to  any 
particular  odor  is  by  no  means  constant  among  different  indi- 
viduals. Many  of  the  lower  animals  pass  their  whole  lives 
in  the  midst  of  odors  which  are  to  man  (in  a  civilized  condi- 
tion) in  the  highest  degree  revolting,  and  will  even  refuse  to 

touch  food  tii^til pit.  is'fsr  Udyimced  iii;;^trddity.' 

'-  '..►'«.«'',  ■■ ,.'        ^,  •■»•       V    '''it  * 

'  Carpenter^  "  J*rinpiple8  of  Physiology."  The  act^pf  vomiting  may  possibly  be  con- 
sidered as  an  exception  \<i  Ahi's  siat/ymentr  y,  '    ;^ :  '  1    .'!*:*! 

«  Mich,  roster,  •' Tcict-Bo61c  01  i'hygiobsyi''  i'3^0;  ^^odd  and  Bowman,  "  Physiologi- 
cal Anatomy." 

'  Carpenter,  "  Principles  of  Human  Physiology." 


ABNORMALITIES  OF  TEE  OLFACTORY  SENSE.  IQI 

It  is  difiicult  to  say  when  effluvia  have  been  completely 
removed  from  the  nasal  passages,  since  it  is  not  unlikely  that 
odorous  particles  (supposing  such  to  exist)  are  often  ab- 
sorbed, or  possibly  dissolved  by  the  mucous  secretion.  It 
frequently  happens,  in  regard  to  odors  and  savors,  that  habit 
lakes  that  agreeable,  and  even  strongly  relished,  which  was 
Lt  first  avoided  ;  the  taste  of  an  epicure  for  game  that  has 
squired  t\\Q  fumet,  for  assafoetida,  garlic,  etc.,  is  an  instance 
this.  A  case  is  reported,  where,  in  a  state  of  hypnotism,  a 
^outh  had  his  sense  of  smell  so  remarkably  heightened  as  to 
)e  able  to  assign,  without  the  least  hesitation,  a  glove  placed 
in  his  hand  to  its  right  owner,  in  the  midst  of  about  thirty 
persons,  the  boy  himself  being  blindfolded  ; '  but  modified 
forms  of  this  excessive  development  of  this  power  of  smell 
are  by  no  means  rare. 

The  word  ''taste"  is  often  used  when  the  word  ''smell" 
should  be  employed.  We  speak  of  tasting  odoriferous  sub- 
stances, such  as  onions,  wines,  etc.,  when  in  reality  we  only 
smell  them  as  we  hold  them  in  the  mouth.  This  is  proved  by 
the  fact  that  the  so-called  taste  of  these  things  is  lost  when 
the  nose  is  held  or  the  nasal  membrane  rendered  inert  by  a 
catarrh.'' 

CLINICAL   POIN^TS   AFFORDED   BY   THE   OLFACTORY   NERVE. 

The  nerves  of  smell  may  become  the  seat  of  disease,  or  may 
simply  manifest  the  presence  of  disease  in  other  parts.  The 
two  conditions,  which  are  clinically  recognized  as  indicative  of 
existing  disease,  are  hypersesthesia  and  anaesthesia — not  of 
the  sensibility  of  the  part,  in  its  generally  accepted  sense,  but 
an  increase  or  decrease  of  the  acuteness  of  the  olfactory  sense." 

^  Carpenter,  op.  cit. 

'•■  Foster,  op.  cit. 

3  According  to  Althaus,  if  the  mucous  membrane  of  the  nose  be  irritated  with  very 
strong  galvanic  currents,  the  taste  of  phosphorus  is  produced ;  but  no  perception  of  odors 
is  perceived,  although  pain,  vertigo,  and  sensations  of  light  may  be  created.  It  is  cus- 
tomary, therefore,  to  use  other  means  for  the  purpose  of  testing  the  acuteness  of  this 
special  sense,  and  the  most  successful  method  consists  of  making  the  patient  smell  differ- 
ent odors,  using  the  nostrils  alternately,  and  avoiding  all  things,  as  tests,  which  would  create 
an  irritation  of  the  filaments  of  the  fifth  nerve,  such  as  ammonia,  acetic  acid,  snuff,  etc. 
(Hence  the  defect  in  Magendie's  experiments  mentioned  on  page  98.)     It  is  advisable 


102  THE  CRANIAL  NERVES. 

To  the  former  condition,  the  temi  " hyper osmia''^  is  applied, 
while  the  latter  is  called  ^'  anosmia^ 

The  condition  of  hyperosmia  is  often  perceived,  as  a  tem- 
porary excitation,  in  patients  recovering  from  some  prolonged 
disease  which  has  exhausted  their  nervous  power,  and  also 
in  the  hysterical  and  insane/  Should  the  presence  of  un- 
natural odors,  or  a  marked  increase  of  the  susceptibility  to 
odors,  exist  in  the  insane,  it  may  indicate  the  existence  of 
some  type  of  neoplasm  involving  the  frontal  lobes  at  the  base 
of  the  cerebrum,  localized  disease  (softening,  as  a  rule)  of  the 
olfactory  bulbs,  or  adhesion  of  the  olfactory  bulbs  to  the  dura 
mater ;  since  all  of  these  conditions  have  been  found  at  autop- 
sies, where  such  symptoms  existed  during  life.  Sander 
reports  a  curious  case,  where  such  a  subject  was  liable  to 
epileptic  attacks,  and  where  the  attacks  were  associated  with 
abnormal  sensations  of  taste ;  the  autopsy  showed  a  tumor 
of  the  left  olfactory  bulb. 

The  abolition  of  the  sense  of  smell  is  a  symptom  of  greater 
frequency,  as  well  as  importance,  than  the  excitation  of  that 
special  sense.  In  rare  cases,  as  in  one  reported  by  Cloquet, 
the  absence  of  the  power  of  smell  may  be  a  congenital  defect. 
Anosmia  may  be  developed,  as  a  temporary  condition,  during 
an  attack  of  acute  catarrhal  inflammation  of  the  nares,  which 
alters  the  character  of  the  membrane,  or,  in  chronic  catarrh, 
by  the  effect  upon  the  natural  moisture  of  the  mucous  lining 
of  the  nose.  It  may  be  present  in  "  Bell's  paralysis,""  since 
the  facial  nerve  no  longer  affords  motor  power  to  the  muscles 
which  dilate  the  nostril,  and  thus  the  entrance  of  air  to  the 
upper  nasal  chamber  is  obstructed.     Anosmia  may  be  one  of 

to  use  odors  which  are  both  agreeable  and  disagreeable  ;  hence  cologne,  camphor,  musk, 
etc.,  on  the  one  hand,  and  valerian,  assafoetida,  turpentine,  sulphureted  hydrogen,  etc.,  on 
the  other  hand,  are  commonly  employed.  It  is  also  customary  to  place  aromatic  substances, 
such  as  coffee,  wine,  liquors,  and  cheese,  within  tJic  mouthy  so  that  the  posterior  part  of 
the  nose  can  perceive  them,  since  the  odoriferous  particles  pass  upward  by  means  of  the 
pharynx,  rather  as  an  imaginary  taste,  however,  than  as  true  olfactory  perceptions. 

'  Frequently  odors  of  the  most  pleasant  character,  such  as  those  of  flowers,  etc.,  may 
occasion  fainting,  nausea,  headache,  or  even  convulsions,  in  this  class  of  patients  ;  while 
odors  nauseating  to  others  may  be  tolerated,  and,  possibly,  preferred  by  them. 

'^  For  the  symptoms  of  this  afifection,  see  pages  of  this  volume  descriptive  of  the  facial 
nerve. 


THE  NERVE  OF   VISION.  1Q3 

the  manifestations  of  tumor  at  the  base  of  the  brain ;  of  ab- 
scess of  the  pituitary  body  (as  reported  by  Oppert) ;  of  syphi- 
litic thickening  of  the  periosteum  and  mucous  lining  of  the 
nose ;  of  lesions  resulting  in  paralysis  of  the  fifth  cranial 
nerve,  for  some  unexplained  reason  ;  of  hysteria  ;  and,  finally, 
\t  certain  types  of  insanity.  A  partial  loss  of  smeU  has  been 
Lnown  to  follow  typhoid  fever  and  meningitis,  in  which  case 
'le  sense  is  usually  regained.  Chronic  rheumatism,  chronic 
initis,  and  traumatism,  have  also  proven  exciting  causes  of 
temporary  but  serious  loss  of  the  sense  of  smell.' 

THE  OPTIC  NERYE. 

The  second  cranial  or  optic  nerve  presents  for  examination 
from  before  backward :  1,  the  optic  nerve  proper ;  2,  the  op- 
tic commissure  ;  and  3,  the  optic  tract. 

The  optic  tracts  of  either  side  extend  from  their  point  of 
origin  in  the  corpora  quadrigemina^  where  they  receive  a  few 
fibers  from  the  optic  thalamus,'  to  the  optic  commissure,  to 
reach  which  point,  each  is  compelled  to  pass  around  the  cms 
cerebri.  In  their  passage  around  the  crus,  each  tract  receives 
a  few  fibers  of  attachment  at  its  anterior  margin  ;  and,  after 
leaving  the  crus,  just  before  the  optic  chiasm  is  formed,  each 
receives  additional  fibers  from  the  lamina  cinerea  and  the  tu- 
ber cinereum. 

The  optic  commissure  or  chiasm  is  formed  by  the  junc- 
tion of  the  two  optic  tracts,  and  from  it  the  two  optic  nerves 
diverge  to  pass  to  their  distribution  in  the  retina  of  either 
eye.  The  construction  of  the  optic  chiasm  is  of  interest  both 
from  an  anatomical  and  a  physiological  standpoint.  In  it, 
four  sets  of  fibers  may  be  demonstrated,  called,  respectively, 

^  In  almost  all  cases,  where  anosmia  affects  both  sides  of  the  nasal  cavity,  the 
sense  of  taste  is  also  impaired.  All  aromatic  forms  of  food  and  wines  have  a  distorted 
flavor.  It  is  claimed  by  Ogle  that  the  pigment  in  the  olfactory  mucous  membrane  has 
some  effect  upon  the  sense  of  smell. 

2  Physiological  experiment  seems  to  point  to  the  angular  gyrus  as  intimately 
connected  with  the  deep  fibers  of  the  optic  nerve  (see  pages  51  and  52  of  this  vol- 
ume). 


104 


THE  CRANIAL  NERVES. 


the  inter -cerebral  fibers,  which  are  situated  at  the  poste- 
rior portion  of  the  commissure,  and  connect  the  two  hemi- 
spheres of  the  cerebrum  ;  the  in- 
ter-retinal fibers,  which  are  situ- 
ated in  the  anterior  portion  of  the 
chiasm,  and  connect  the  retina  of 
one  eye  with  that  of  the  other  ;  the 
longitudinal  fibers,  which  lie  on 
the  external  side  of  each  of  the 
optic  tracts,  and  connect  the  ret- 
ina with  the  cerebral  hemisphere 
of  the  same  side ;  and,  finally, 
the  decussating  fibers,  which  pass 
through  the  center  of  the  optic 
chiasm,  and  serve  to  connect  the 
retina  of  each  eye  with  the  oppo- 
site cerebral  hemisphere. 

The  optic  nerve  proper  arises 
from  the  anterior  part  of  the  optic 
commissure  and  enters  the  optic 
foramen,  in  company  with  the  oph- 
thalmic artery,  being  surrounded 
by  a  tubular  process  of  dura  mater, 
which,  as  the  nerve  enters  the  or- 
bit, subdivides  and  forms  both  the 
sheath  of  the  nerve  and  the  peri- 
osteum of  the  orbit.  The  nerve 
pierces  the  sclerotic  and  choroid  coats  of  the  eye,  about  one 
tenth  of  an  inch  to  the  inner  side  of  the  axis  of  the  eye,  and 
then  divides  into  numerous  small  fibrils,  which  appear  to 
spread  themselves  out  from  the  papilla  of  the  retina  some- 
what like  the  spokes  of  a  wheel. 

In  the  accompanying  diagram,'  which  is  not  given  as  an 
accurate  representation  of  the  parts,  but  rather  as  an  aid  to 
memory,  and  to  render  plain  what  words  alone  might  make 
obscure,  the  fibers  of  the  optic  nerve  are  seen  to  enter  the  re- 


FiG.  31. —  Optic  tracts,  commissure^ 
and  nerves.     (Hirschfeld.) 

1,  infundibulum ;  2,  corpus  cinerc- 
um  ;  3,  corpora  albicantia ; 
4,  cerebral  peduncle  ;  5,  tuber 
annulare  ;  6,  optic  tracts  and 
nerves,  decussating  at  the  com- 
missure, or  chiasm ;  V,  motor 
oculi  communis  ;  8,  patheticus ; 
9,  fifth  nerve ;  10,  motor  oculi 
externus  ;  11,  facial  nerve ;  12, 
auditory  nerve;  13,  nerve  of 
Wrisberg  ;  14,  glosso-pharyn- 
geal  nerve ;  15,  pneumogastric ; 
16,  spinal  accessory ;  17,  sub- 
lingual nerve. 


*  After  Weber,  of  Darmstadt.     (See  page  105.) 


DISTRIBUTION  OF  OPTIC  FIBERS.  105 

tina  at  the  point  designated  by  the  letter  P,  which  is  called 
the  papilla,  since,  at  this  point,  the  retina  is  slightly  raised 
above  the  remaining  portion.  This  papilla  is  not  in  the  exact 
center  of  the  retina,  since  that  point  is  reserved  for  the  macula 
lutea.m  the  center  of  the  so-called  "  yellow  spot  of  Sommer- 
ing,"  where  the  most  exact  vision  of  external  objects  is  ob- 


FiG.  32. — Diagramof  the  decussation  at  Fig.  33. — A   diagram  to  show  the  course  of 
the  optic  commissure.    (After  Flint.)  the  optic  Jibers  in  the  retina.    (After  Weber.) 

The  dotted  lines  show  the  four  direc-  p,  the  papilla,  where  the  optic  nerve  enters  ; 
tions  of  the  fibers.  m,  the  macida  lutea. 


tained  ;  but  it  is  placed  to  the  inner  side  of  the  center.,  and 
nearly  on  the  same  level  with  the  yellow  spot.  It  will  be 
seen  that  those  nerve  fibers  which  are  distributed  to  the  yellow 
spot  of  Sommering  are  directed  outward  in  a  nearly  straight 
line  from  the  papilla,  as  are  also  those  which  supply  the  part 
internal  to  the  papilla  ;  but  that,  in  order  to  avoid  crossing 

IA^e  yellow  spot,  the  fibers  are  compelled  to  pass  in  a  more 
Br  less  curved  direction  to  the  other  parts  of  the  retina, 
^hereas,  if  the  papilla  were  in  the  exact  center,  the  fibers 
Kf  the  optic  nerve  would  probably  have  been  straight,  and 
arranged  as  the  radii  of  a  circle.  This  arrangement  of  the 
optic  fibers  differs  from  that  described  by  some  of  the  text- 
books on  physiology,  one  of  which,  to  my  knowledge,  states 
that  they  are  arranged  as  a  plexus,  and  that  the  frequent 
inosculation  gives  a  peculiar  ''net-like"  appearance  to  the 


106  TEE  CRANIAL  NERVES. 

optic  fibers/  Probably  the  fact  that  the  nerve  fibers  lose 
their  sheaths  as  soon  as  they  enter  the  retina,  and  thus, 
unless  they  be  previously  stained,  afford  some  difficulty  in 
tracing  them,  explains  the  error  in  description. 

REFLEX   ACTS   EXCITED   BY  THE   OPTIC   NERVE. 

The  optic  nerve  differs  from  the  olfactory  nerve  in  one  im- 
portant respect,  viz.,  in  its  power  of  conveying  impressions 
which  create  reflex  muscular  movements.''  The  motions  of  the 
iris  are  always  influenced  by  the  amount  of  light  which  enters 
the  eye,  and  which  thus  affects  the  optic  nerve  filaments. 
When  the  optic  nerve  is  divided,  the  pupil  immediately  con- 
tracts^ unless  the  third  cranial  nerve,  which  controls  its  move- 
ments, is  also  severed,  when  the  iris  fails  to  be  so  affected.' 
In  rare  cases  of  disease,  where  the  sight  of  one  eye  has  been 
destroyed  by  some  lesion  of  the  optic  nerve,  the  pupil  of  the 
affected  eye  will  be  found  to  move  in  unison  with  the  unin- 
jured eye  ;  but  this  effect  is  to  be  attributed  to  a  motor  impulse 
created  by  the  influence  of  light  upon  the  retina  of  the  normal 
organ.  In  some  cases  also,  where  the  tissue  of  the  hemi- 
spheres has  undergone  changes  which  render  the  perception 
of  objects  impossible,  the  pupil  may  still  be  seen  to  respond 
to  the  variations  of  the  quantity  of  light  which  enters  the 
chamber  of  the  eye  ;  thus  showing  that  the  optic  nerve  alone 
is  required  to  create  the  reflex  act  upon  the  pupil  through 
the  third  nerve,  irrespective  of  the  brain. 

In  addition  to  the  power  of  the  optic  nerve  to  cause 
changes  in .  the  pupil,  there  is  still  another  form  of  reflex  act 
which  deserves  notice,  viz.,  its  power  of  producing  contraction 
of  the  orbicular  is  palpebrarum  muscle.  This  is  perceived 
when  an  excessive  quantity  of  light  renders  the  effect  upon 

*  Carpenter,  op.  cit. 

'  Carpenter,  op.  cit.  (It  is  a  question  M  fainting  and  vomiting  can  not  be  often  justly 
regarded  as  reflex  muscular  acts,  dependent  upon  the  sensations  perceived  through  the 
olfactory  nerve.) 

^  Doubtless  on  account  of  the  simultaneous  division  of  sympathetic  nerve  fibers,  which 
are  probably  derived  from  the  fifth  nerve  ;  these  accompany  the  optic  nerve  and  thus  con- 
trol the  dilating  fibers  of  the  iris. 


I 


DECUSSATION  OF  OPTIC  FIBERS  107 


the  retina  one  of  pain,  or  when  objects  to  be  perceived  are 
\    brought  into  too  close  proximity  to  the  eye.     Thus,  in  photo- 
'.     phobia,  the  peculiar  half-closed  condition  of  the  eye  is  not 
purely  a  voluntary  act,  as  the  eye  is,  at  the  same  time,  rolled 
upward  and  inward  to  a  much  greater  extent  than  can  be  per- 
formed in  response  to  a  merely  voluntary  effort, 
b^    The  act  of  sneezing  may  often  be  excited  by  the  visual 
P^ense,  when  a  sudden  exposure  of  the  eyes  to  a  strong  light 
occurs.    That  this  reflex  phenomenon  is  due  to  the  excitation 
I     of  the  optic,  and  not  to  the  olfactory  nerve,  is  proven  by  the 
fact  that,  unless  the  ligM  he  seen,  the  attack  of  sneezing  does 
not  take  place. 

DECUSSATIOiT   OF  THE   OPTIC   FIBEKS. 

The  object  of  the  decussation  of  the  fibers  of  the  optic 

nerve  has  been  explained  by  WoUaston,'  Mayo,"  and  others, 

,     as  an  arrangement  on  the  part  of  Nature  to  have  the  fibers, 

which  spring  from  each  optic  ganglion,  distributed  to  the  cor- 

fcsponding  side  of  each  retina  ;  the  right  optic  ganglion  be- 

mg  thus  associated  with  the  outer  portion  of  the  retina  of  the 

tight  eye  and  the  inner  portion  of  the  left  eye,  while  the  left 
^nglion  is  distributed  to  the  outer  portion  of  the  left  eye 
and  the  inner  portion  of  the  right  eye.  If  this  be  demon- 
strated as  true,  each  optic  ganglion  must  perceive  objects  on 
the  side  opposite  to  it ;  since  the  images  of  things  seen  by  the 
retina  must  fall  upon  the  outer  side  of  the  left  eye,  when 
placed  upon  the  right  side  of  the  eye,  and  vice  versa.  ^ 

A  similar  decussation  of -nerve  fibers  is  known  to  exist  in 
both  the  posterior  horns  of  the  spinal  cord  and  also  in  the 
anterior  pyramids  of  the  medulla  oblongata  ;  and  the  same 
arrangement  in  the  optic  nerves,  which  are  known  to  be  of 
the  greatest  value  in  preserving  a  harmony  of  motion  through- 
out the  body,  may  be  for  the  object  of  bringing  the  visual  im- 
pressions into  a  more  direct  and  proper  accord  with  the  motor 

^  "  Philos.  Trans.,"  1824. 
'■^  See  Carpenter's  "  Physiology." 

^  See  bearing  of  this  arrangement  on  diagnosis  of  cranial  tumors,  later  on  in  this 
chapter. 


108  THE  CRANIAL  NERVES, 

apparatus.  In  support  of  this  view,  it  is  found  tliat  in  the 
invertebrate  animals,  where  the  optic  fibers  do  not  decus- 
sate, no  decussation  of  fibers  exists  in  the  general  motor 
system. 

In  some  animals,  where  the  two  eyes  have  an  entirely  dif- 
ferent field  of  vision,  the  decussation  of  the  fibers  from  each 
optic  ganglion  is  found  to  be  complete,'  the  longitudinal  set 
being  absent,  and  the  whole  of  the  fibers  from  each  ganglion 


NASAL  SIDE          / 

'       N 

\.\ 

_  OPTIC  NERVE. 

OF   OPTIC j 

< ^ 

/-^ 

FORAMEN.            \ 

^ 

V)J 

OPHTHALMIC 
ARTEFfY. 

Fig.  34. — Relation  of  nerve  and  artery  in  the  optic  foramen. 

i 


ARTERIA  -/TrSl        O       \C\ 

CENTRALIS -\^^JI-— -*^        RJ 

RETINAE.  (^^      ^^  J 

1.2.  J.4.5.ClLIARr  ARTERIES. 
Fig.  35. — Relations  of  optic  nerve  to  vessels  in  the  orbit, 

passing  into  the  opposite  eye.  This  arrangement  can  be  per- 
ceived in  almost  all  of  the  bird  species '  and  in  some  of  the 
osseous  fishes. 

RELATIONS   OF   OPTIC   NERVE   IN  THE   ORBIT. 

The  relations  of  the  optic  nerve  to  blood-vessels  may  have 
often  a  bearing  upon  vision.     It  passes  through  the  optic 

'  The  decussation  of  the  fibers  of  the  optic  nerve  seems  also  to  be  influenced  largely 
by  the  extent  of  the  field  of  vision  which  can  be  covei'ed  by  both  eyes  simultaneously. 
The  bundle  of  decussating  fibers  differs,  in  its  relative  size,  from  the  bundle  of  non-de- 
cussating fibers,  in  different  animals,  who  possess  a  stereoscopic  perception  of  objects 
(their  vision  being  binocular) :  and  the  extent  of  the  field  of  binocular  vision  seems  to 
explain  this  fact.  It  is  said  that  certain  birds  (as  the  hawk,  for  example)  have  an  addi- 
tional power  of  binocular  vision  affoi'ded  them  by  means  of  two  maculae  lutea?  in  each 
retina  ;  so  that,  having  two  spots  of  distinct  vision  in  each  eye,  the  two  eyes  can  the  more 
readily  focus  suddenly  upon  any  object. 

'  Solly,  "  The  Human  Brain  "  (Am.  edition). 


f 


RESULTS   OF  DEFECTIVE  VISION.  10& 

foramen  in  company  with  the  ophthalmic  artery,  and  is  sur- 
rounded,  for  the  balance  of  its  length,  by  the  ciliary  arteries, 
which  lie  in  close  relation  with  it.  It  is  also  pierced  by  the 
arteria  centralis  retince,  which  is  thus  enabled  to  reach  the 
papilla  of  the  retina,  and,  from  that  point,  to  ramify  through- 
out that  membrane. 

Ilt  can  be  readily  understood,  therefore,  how  liable  would 
any  vascular  growth  within  the  orbit  to  press  upon  the 
fibers  of  the  optic  nerve,  or  to  create  sympathetic  changes  in 
the  vessels  of  the  retina  itself ;  while,  as  an  anatomical  fact, 
the  enormous  collateral  circulation  which  exists  on  account 
of  the  frequent  anastomosis  in  this  region,  renders  such  vas- 
cular growths  within  the  orbit  by  no  means  uncommon. 

ANATOMICAL   DEFECTS   OF   VISION   AND   THEIR   CONSEQUENCES. 

A  ray  of  light  falling  upon  the  retina  strikes  the  expansion 
of  the  fibers  of  the  optic  nerve,  and  creates  what  may  be  called 
a  sensation  of  light.  What  this  sensation  is,  it  is  not  within 
the  province  of  this  work  to  discuss,  nor  is  it  possible,  from 
our  present  enlightenment,  to  explain  how  the  brain  trans- 
forms impressions,  received  from  the  fibers  of  the  different 
nerves  of  special  sense,  into  an  actual  recognition  of  either 
smell,  sight,  taste,  or  hearing.  This  should  not  deter  us,  how- 
ever, from  carefully  studying  all  the  mechanical  ingenuity 
which  Nature  has  shown  in  the  arrangement  of  certain  parts, 
or  from  attempting  to  interpret  her  aims  and  purposes  when 
any  such  subject  of  inquiry  seems  to  be  presented. 

There  are  certain  practical  points  pertaining  to  the  mechan- 
ism of  vision  concerning  which  every  physician  should  be  in- 
telligent ;  since  a  recognition  of  existing  optical  defects  and 
their  bearings  upon  health  will  often  enable  the  medical  ad- 
viser to  guide  aright  those  consulting  him,  when  otherwise 
serious  consequences  might  follow  the  very  lack  of  this  prac- 
tical knowledge. 

The  most  common  optical  defects '  are,  undoubtedly,  hy- 
peropia, or  far-sightedness;   myopia,    or  near-sightedness*, 

1  Bowman  and  Todd,  "  Physiological  Anatomy." 


110  TEE  CRANIAL  NERVES. 

and  astigmatism^  or  imperfect  perception  of  objects  in  cer- 
tain meridians  of  vision. 


Fig.  36. — Diagram  to  illustrate  congenital  or  acquired  defects  in  the  antero-posterior  diam- 
eter of  the  eye.  The  black  line  represents  the  normal  line  of  the  eye.  No.  1  represents 
the  hypcropic  eye ;  2,  the  myopic  eye ;  3,  the  optic  nerve. 

The  first  of  these  conditions  indicates,  as  a  rule,  a  congeni- 
tal or  acquired  diminution  in  the  antero-posterior  axis  of 
the  eye.  Thus,  as  age  advances,  the  eye  either  naturally 
becomes  flattened,  or  the  ability  to  accommodate  for  distance 
becomes  impaired,  and  vision  necessarily  becomes  hyperopic  ; 
but,  in  many  cases,  children  are  bom  with  this  deformity, 
which  often  goes  too  long  unrecognized.  Were  Nature  not 
able  to  compensate  for  this  abnormality  by  means  of  the  cili- 
ary muscle,  which,  by  altering  the  shape '  of  the  crystalline 
lens  of  the  eye,  is  enabled  to  increase  its  convexity,  and  thus 
artificially  to  focus  near  objects,  such  cases  would  be  imme- 
diately made  known  by  the  inability  of  the  patient  to  read 
or  even  to  see  near  objects  with  distinctness.  But  such  cases 
go  on  from  year  to  year,  struggling,  with  the  aid  of  this  mus- 
cle, to  see,  and  thus  wearing  out  their  vital  energy ;  trying 
to  excel  in  their  studies,  only  to  fail  from  the  fatigue  which 
attempts  at  study  bring  about,  which  they  themselves  or  their 
parents  can  not  explain,  and  which  often  causes  them  to  in- 
cur bodily  chastisement ;  and  seeking,  as  a  relief,  out-of-door 
amusements,  in  which  they  usually  excel,  since  little  muscu- 
lar effort  is  required  to  perceive  objects  at  a  distance. 

*  Foster,  Volekers,  Hensen,  and  Hock  claim  that  the  increased  convexity  of  the  lens 
is  due  to  the  relaxation  of  the  suspensory  ligament,  thus  allowing  the  lens  to  bulge  for- 
ward from  its  own  elasticity. 


RESULTS  OF  DEFECTIVE  VISION.  ^ 

How  cruel  and  injurious  to  health  must  be  compulsory 
education  to  such  a  one,  till,  by  the  aid  of  properly  adjusted 
glasses,  reading  becomes  a  pleasure ;  study  no  longer  a  bur- 
den, but  a  joy  ;  and  nervous  headache,  throbbing  in  the  orbit, 
double  vision,  and  other  evidences  of  nervous  prostration,  are 
numbered  as  among  the  things  of  the  past ! ' 

On  the  other  hand,  myopic  patients  can  not  see  objects  at, 
a  distance,  since  their  eyes  are  too  convex ;  but  only  when 
placed  close  to  the  eyes  are  the  beauties  of  outline  fully  per- 
ceived, and  distinct  vision  rendered  possible.  Out-of-door 
exercise  is,  to  children  of  this  type,  a  burden  and  a  disap- 
pointment, since  they  can  not  enjoy  Nature  in  her  most  beau- 
tiful aspects,  nor  indulge  in  sports  without  danger,  which  to 
the  healthy  child,  with  perfect  vision,  is  harmless.  Such 
children  seek  enjoyment  in  books,  the  contents  of  which  can 
be  seen  by  them  and  easily  read ;  the  fields  are  discarded  for 
the  parlor ;  the  enforced  retirement  is  wrongly  construed  by 
the  parents  and  physician  as  an  indication  of  precocity  and  a 
taste  above  that  of  the  romping  child ;  the  health  is  imper- 
iled, the  intellect  weakening  by  undue  strain,  and  the  mind 
made  one  of  ideals  rather  than  of  realities,  since  pictures  and 
book  representations  are  to  them  Nature  in  her  true  aspects.' 

Astigmatism  is  a  condition  due  to  the  fact  that  either  the 
surfaces  of  the  cornea  or  of  the  crystalline  lens  are  not  of  the 
same  curvature^  but  are  more  convex  in  some  portions  than 
in  others,  or  in  the  perpendicular  meridian  than  in  the  hori- 
zontal. This  abnormality  of  contour  causes  a  distortion  of 
the  image  of  objects  in  the  field  of  vision.  If  black  lines,  of 
equal  width,  be  drawn  parallel  with  each  other,  and  several 
placed  perpendicularly  on  one  portion  of  a  page  and  several 
horizontally  on  another  portion  of  the  same  page,  such  an  eye 
will  see  one  or  the  other  set  either  less  distinctly  as  to  outline, 
or  one  set  will  appear  darker  than  the  other. 

Almost  all  eyes  are  slightly  astigmatic^  and  generally  with 
the  greatest  convexity  in  the  vertical  meridian.  And  the  same 
irregularity  in  lenses  can  be  demonstrated  by  attempting  to 

^  See  article  by  Dr.  Loring,  "  Harper's  Mag.,"  August,  \^1^. 


112  THE  CRANIAL  NERVES. 

focus  light  from  a  luminous  point,  when  the  image  will  be 
found  to  be  radiated,  instead  of  a  perfect  circle,  as  it  should 
be  from  a  perfect  lens. 

In  choosing  spectacles,  for  the  purpose  of  correcting  errors 
of  the  eye,  it  is  of  great  consequence  not  to  make  an  over- 
compensation ;  for  this  has  a  tendency  to  increase  the  defect, 
besides  occasioning  great  fatigue  in  the  employment  of  the 
sight. 

From  observations  previously  made  as  to  the  mechanism 
of  the  action  of  the  ciliary  muscle  upon  the  lens,  by  which 
vision  is  accommodated  for  near  objects  in  case  the  eye  is 
normal,  it  may  be  understood  why  all  power  of  accommoda- 
tion of  vision  is  lost  after  the  operation  for  cataract. 

A   TEST   FOR   MYOPIA    AND   HYPEROPIA. 

B  F  P  T  Z  D 
D  I.  T  Z  F  P  E 
B  E  P  F  Z  T  I. 

The  normal  eye  should  read  letters  of  this  kind  and  size 
at  twenty  feet.  Vision  is  then  said  to  be  normal.  If  the  eye 
can  not  do  this  at  twenty,  but  can  at  ten  feet,  then  vision  is 
ten  twentieths,  or  one  half  of  the  normal,  and  so  on. 

To  test  the  eyes,  place  the  letters  at  twenty  feet  dis- 
tance, in  a  good  light.  Try  iirst  one  eye,  and  then  the 
other. 

Any  eye  which  can  not  read  the  letters  fluently  at  this  dis- 
tance deviates  from  the  normal  standard,  and  should  have  a 
thorough  examination. 

To  test  for  the  defect  which  has  been  mentioned  in  the 
foregoing  remarks  as  astigmatism,  place  the  drawing,  show- 


TESTS  FOR  DEFECTIVE   VISION.  II3 

ing  parallel  lines  arranged  vertically  and  liorizontally,  at  fif- 
teen or  twenty  feet,  and  be  sure  to  test  each  eye  separately, 

A   TEST   FOR   ASTIGMATISM. 


These  lines  should  appear  equally  distinct ;  that  is,  those 
running  vertically  should  look  as  black  and  clearly  defined  as 
those  which  run  horizontally,  and  vice  versa.  If,  however, 
there  is  any  difference  between  the^i  as  to  shade  of  color  or 
distinctness  of  outline,  the  eye  is  astigmatic,  and  the  greater 
the  difference,  the  greater  the  degree.  Such  an  eye  as  this 
requires  peculiar  glasses,  which  can  only  be  determined  by  a 
careful  examination,  and  which  have  to  be  selected  to  fit  each 
case.  It  may  be  that  a  person  is  not  astigmatic  for  vertical  or 
horizontal  lines,  but  is  for  those  running  obliquely.  To  test 
this,  turn  the  drawing  so  that  what  are  ordinarily  the  vertical 
lines  shall  run  obliquely,  say,  at  an  angle  of  forty-five  de- 
grees. 

If,  now,  this  were  all,  it  would  be  a  simple  matter  for  the 


114  THE  CRANIAL  NERVES. 

parent  or  teacher  to  determine  just  what  children  needed  a 
careful  examination,  but,  unfortunately,  there  are  a  large 
number  of  children  who,  as  has  been  already  explained,  have 
a  deficiency  of  optical  power,  but  who  can,  nevertheless,  neu- 
tralize this  deficiency  by  an  effort,  so  that  they  can  see  at  as 
great  a  distance  and  as  clearly  as  those  who  have  normal  eyes. 
These  are  those  who  most  suffer  from  headache,  and  from  all 
the  ills  of  a  nervous  nature  which  have  been  detailed  in  the 
foregoing  remarks.  The  only  satisfactory  way  out  of  the  dif- 
ficulty would  appear  to  be,  that  every  child  should  have  the 
optical  condition  of  the  eye  and  the  amount  of  vision  deter- 
mined, before  school  life  begins,  by  some  competent  person 
trained  in  the  methods  of  making  these  examinations. 

CHANGES  IN  THE   PUPIL. 

The  pupil  of  the  eye  may  be  seen  to  dilate  when  distant 
objects  are  to  be  perceived,  and  to  contract  when  near  objects 
are  inspected,  since,  by  so  doing,  the  amount  of  light  which 
enters  the  eye  is  regulated,  and  the  distinctness  of  the  image 
is  thus  increased. 

Irritation  of  the  optic  nerve,  by  an  excessive  quantity  of 
light,  also  creates  contraction  of  the  pupil ;  while  the  same 
condition  may  be  the  result  of  simply  turning  the  eyeball 
inward.' 

In  the  early  stages  of  anaesthesia'  from  chloroform,  in 
alcoholic  excitement,  in  poisoning  from  morphia,  physostig- 
min,  and  some  other  drugs,  and,  finally,  in  deep  slumber,  the 
pupils  are  found  to  be  contracted. 

Dilatation  of  the  pupil  may  be  dependent  upon  a  dim 
light,  an  attempt  to  view  distant  objects,  emotional  excite- 
ment, the  latter  stages  of  anaesthesia  from  chloroform,  and 
from  belladonna  poisoning  and  that  of  drugs  of  similar 
action  ;  while  it  may  also  occur  in  all  conditions  creating  an 

»  "  I  may  here  say  that  small  and  unequal  pupils  in  a  person  of  middle  age,  from 
twenty-five  to  sixty,  should  lead  to  an  inquiry  into  the  possible  existence  of  one  of  three 
morbid  states,  viz. :  paralytic  dementia  (or  general  paralysis),  sclerosis  of  the  posterior  col- 
umns, and  cardiac  or  aortic  disease  (intra-thoracic  disease)."     (E.  C.  Seguin.) 

2  Mich.  Foster,  "  Text-Book  of  Physiology." 


VISUAL  SENSATIONS.  115 

excess  of  aqueous  humor  within  the  eye,  and  during  dyspnoea 
and  excessive  muscular  exertion. 

The  mechanism  of  the  action  of  the  pupil  will  be  more 
properly  considered  under  the  description  of  the  third  nerve, 
which  furnishes  it  with  motor  power. 

VISUAL   SENSATIONS   AND   THEIR   MODinCATIONS. 

Shadows  thrown  upon  the  retina  are  perceived  as  specks  in 
the  vision,  the  so-called  muscce  volitantes^  They  may  arise 
from  tears  upon  the  cornea,  a  temporary  unevenness  of  the 
cornea  after  the  eyelid  has  been  pressing  upon  it,  imperfec- 
tions of  the  lens  or  its  capsule,  and  from  shadows  produced 
by  the  margin  of  the  iris,  especially  if  it  be  imperfect. 

They  are  distinguished  chiefly  by  their  almost  continual 
change  in  position,  when  the  head  is  moved  up  and  down, 
and  by  a  tendency  to  entire  disappearance  when  an  effort  is 
made  to  fix  the  vision  upon  them. 

That  point  on  the  retina,  the  papilla,  where  the  optic  nerve 
pierces  it,  is  called  the  ''blind  spot,"  "  since  no  sensations  of 
light  can  be  perceived  in  that  locality. 

In  that  portion  of  the  retina,  the  "macula  lutea,"  where 
the  images  to  be  perceived  by  the  optic  nerve  fall  most  direct- 
ly, and  where  most  of  our  visual  perceptions  are  therefore 
gained,  a  markedly  yellow  pigment  exists,  which  tends  to 
absorb  some  of  the  greenish-blue  rays  of  light ;  hence  what 
we  perceive  as  white  in  color  is,  in  reality,  more  or  less  yellow. 

When  pressure  is  forcibly  exerted  upon  the  eyeball,  the 
whole  retina  speedily  becomes  insensible  to  light.  This  fact 
has  been  explained  as  the  result  of  a  loss  of  the  conductive 
power  of  the  nerve  structures.  Exner,  however,  endeavors  to 
use  this  fact  as  the  basis  of  an  argument  to  prove  that  the 
sensation  of  light  is  the  result  of  some  substance  (as  yet  un- 
determined) within  the  retina,  whose  production  is  tempora- 
rily arrested  by  any  pressure  upon  the  eye  which  is  suffi- 
ciently forcible  to  occlude  the  vessels  of  the  retina,  and  thus 
to  interfere  with  its  nutrition. 

1  Bowman,  "  Phys.  Anat."  ^  Helmholtz,  "  Phys.  Optik." 


116 


THE  CRANIAL  NERVES. 


THE   PERCEPTION   OF   COLOR. 


The  subject  of  color  blindness^  which  is  to-day  assuming 
great  importance,  naturally  suggests  to  the  inquiring  mind — 
by  what  anatomical  arrangement  are  the  optic  nerve  libers 


Fig.  37. —  Crystalline  lens,  antenor  view.    (Babuchin.) 

informed,  through  the  aid  of  the  coats  of  the  retina,  of  the 
perception  by  that  membrane  of  the  color  of  images  ? 

That  the  retinae  of  animals  possessed  color  was  first  noticed 
by  Krohn,  as  early  as  1839  ;  but  the  matter  was  not  regarded  as 
of  any  physiological  importance  until  Boll,  in  1876,  announced 
that  the  retina  of  all  vertebrated  animals  possessed  a  purplish 
color,  which  faded  in  the  light,  but  which  darkness  restored. 
He  concluded  that  the  color  must  be  largely  concerned  in  the 
act  of  vision.' 

The  subsequent  experiments  of  Kuhne  upon  this  subject 
seem  to  have  partially  verified  this  discovery,  but  exactly  what 

^  A  very  interesting  article,  by  my  friend  Dr.  Ayres,  of  this  city,  appeared  in  the  "  New- 
York  Med.  Jour."  (December,  1880),  in  which  the  physiological  action  of  the  vitual  pw-ple 
was  discussed ;  its  function  is  here  stated  to  be  a  photo-chemical  one,  designed  to  accom- 
modate vviion  to  different  degrees  of  light,  since  it  is  capable  of  changing  and  regaining  its 
original  color  when  circumstances  demand  it  (an  intensity  of  light  or  an  approach  to 
darkness  causing  rapid  effects  upon  it). 


THE  VISUAL  PURPLE. 


ir 


its  function  is  may  yet  be  considered  a  subject  of  investiga- 
tion. A  prominent  author  says  of  this  matter:  ''It  is  very 
tempting  to  connect  this  visual  purple  with  color  vision  ;  but 


Fig.  38. — A.  Vertical  section  of  the  retina. 
(IT.  Muller.) 


B.  Connection  of  the  rods  and  cones  of 
the  retina  with  the  nervous  elements. 
(Sappey.) 


1,  1,  layer  of  rods  and  cones;  2,  rods;  3, 
7,  inter-granule  layer  (cone-fiber  plexus): 
granular  gray  layer;  11,  layer  of  nerve 
optic  nerve  ;  13,  membrana  Hmitans. 

1,  1,  2,  3,  rods  and  cones,  front  view  ;  4, 
the  external  and  internal  granule  layers ; 
jaccnt  cells;  10,  13,  nerve  cells,  connected 
filaments  connecting  cells  of  the  external 
the  figure);  14,  15,  16,  17,  18,  19,  20,  22, 
nected  with  the  cells  of  the  granule  layers, 
fibers. 


cones ;  4,  4,  5,  6,  external  granule  layer ; 
;  8,  internal  granule  layer;  9,  10,  finely 
cells;  12,  12,  12,  12,  14,  14,  fibers  of  the 

5,  6,  rods,  side  view ;  7,  7,  8,  8,  cells  of 
9,  cell,  connected  by  a  filament  with  sub- 
with  cells  of  the  granule  layers;  11,  21, 
and  internal  granule  layers  (12  is  not  in 
23,  24,  25,  26,  a  rod  and  a  cone,  con- 
with  the  nerve  cells,  and  with  the  nerve 


we  know  that  our  color  vision  is  most  exact  in  the  fovea  cen- 
tralis^ where  the  retina  consists  of  cones  alone,  which  are  des- 
titute of  this  visual  purple." ' 


10 


Mich.  Foster,  op.  cit. 


118  THE   CRANIAL  NERVES. 

While  no  positive  statements  can  as  yet  be  made  as  to  the 
function  of  that  layer  of  the  retina  known  as  ''the  rods  and 
cones  of  Jacob,"  still  authorities  seem  inclined  to  attribute  to 
the  eones^  rather  than  to  the  rods,  the  power  of  perceiving- 
color.  It  is  known  that  these  cones  are  absent  in  the  retina 
of  nocturnal  animals  ;  while,  in  the  eyes  of  birds  and  reptiles, 
globules  containing  color  are  found  within  the  cones.  More- 
over, the  "fovea  centralis"  in  the  human  eye  is  destitute  of 
rods. 

To  explain  our  perception  of  color,  the  hypothesis  was  first 
made  by  Young  that  there  existed  in  the  retina  the  power  of 
perceiving  three  distinct  color  sensations^  which,  being  parts 
of  the  spectrum,  could,  by  a  proper  admixture  of  certain  pro- 
portions of  each,  produce  white ;  he  further  supposed  that 
there  existed  three  distinct  sets  of  nerve  fibers^  each  set  being 
sensitive  to  a  primary  color  sensation,  viz.,  to  wave  lengths 
of  a  certain  length.  Helmholtz  has  done  much  to  bring  this 
theory  to  notice,  so  that  the  theory  is  known  now  as  the 
'*  Young-Helmholtz  theory,"  rather  than  by  the  name  of  the 
originator  of  the  hypothesis  alone.  The  fact  that  the  most 
careful  microscopical  examinations  of  the  retina  fail  to  dis- 
cover the  existence  of  sets  of  fibers,  which  differ  in  their  ana- 
tomical construction,  seems  to  place  this  theory  rather  on  the 
basis  of  a  pretty  hypothesis  than  that  of  an  acknowledged 
fact. 

Hering  and  Aubert '  have  discarded  the  Young-Helmholtz 
theory,  however,  and  have  attempted  to  explain  the  percep- 
tion of  color  by  a  process  of  disintegration^  in  one  set  of 
colors,  and,  in  another,  by  a  process  of  assimilation  of  a 
property  of  the  retina,  which  is  denominated  ""visual  sub- 
stance,^^ 

All  persons  vary  much  in  their  power  of  discriminating 
and  appreciating  color  ; ""  but  only  those  can  properly  be  said 
to  be  "color  bLind"who  regard  colors  as  similar  which  to 
most  people  would  be  glaringly  distinct.     Thus,  red  and  green 

'  "  Physiologic  der  Netzhaut,"  1865. 

'  Seebeck,  Wartmann,  Miiller's  *' Pliysiology "  (Baly's  edition). 


COLOR  VISION. 


119 


120  THE  CRANIAL  NERVES. 

are  commonly  mistaken  for  each  other;  while  purple  and 
bhie,  red  and  brown,  and  brown  and  green,  are  often  detected 
from  one  another  with  difficulty,  if  at  all. ' 


Any  stimulation  of  the  optic  nerve  or  of  the  retina,  if  suffi- 
ciently intense,  may  give  rise  to  certain  sensations,  which  are 
mistaken  for  actual  vision.  As  examples  of  this  fact,  a  blow 
in  the  eye  or  on  the  back  of  the  skull  will  often  make  the 
injured  person  ''  see  stars  "  or  have  flashes  of  light  apparently 
cross  the  field  of  vision. 

Foster ""  mentions  a  case,  where,  by  a  voluntary  compres- 
sion of  the  eyeball  by  the  orbicularis  palpebrarum  muscle, 
gorgeous  visions  of  flowers  and  landscapes  could  be  produced. 

EFFECT   OF   OPTIC   NERVE   ON    COORDINATION. 

The  optic  nerve  may  become  a  means  of  vertigo,  when 
objects  are  caused  to  pass  rapidly  before  the  field  of  vision, 
as  in  viewing  a  waterfall,  being  rapidly  whirled,  etc.  This 
subject,  however,  will  be  more  fully  considered,  with  points 
of  interest  pertaining  to  the  auditory  nerve,  since  Meniere's 
malady  is  more  often  dependent  upon  disease  of  the  acoustic 
apparatus. 

Goltz '  has  shown,  by  experiments  upon  birds  whose  heads 
were  artificially  secured  in  an  abnormal  position,  that  they  at 
once  become  incapable  of  orderly  flight,  thus  further  confirm 
ing  the  apparent  connection  between  the  special  sense  of  sight 
and  those  muscular  movements  which  require  the  exercise  of 
the  power  of  coordination. 

EFFECT  OF  THE   OPTIC   NERVE   ON  THE   LACHRYMAL   APPARATUS. 

The  contraction  of  the  orbicularis  muscle  tends  to  press 
the  tears,  which  the  lachrymal  canals  contain,  onward  toward 
the  nasal  duct ;  and  they  dilate  to  receive  a  fresh  quantity 
during  the  relaxation  of  this  muscle.     Thus  the  act  of  wink- 

'  Taylor's  "  Scientific  Memoirs."  «  Op.  cit 

3  Pflugei's  "  Archiv,"  1873,  as  quoted  by  Foster. 


NERVES  OF  LACHRYMAL  APPARATUS. 


121 


Ing,  wMcli  usually  precedes  any  special  attempt  to  see  with 
distinctness,  by  calling  the  orbicularis  palpebrarum  muscle 
into  play,  assists  in  cleansing  the  eye  of  any  excess  of  tears. 
It  has  been  stated  by  Demtschenko, '  that,  during  the  closure 
of  the  eyelid,  a  peculiar  arrangement  of  the  muscular  fibers 
tends  to  keep  the  lachrymal  canals  open,  and  thus  to  act  as 
an  aid  to  the  orbicularis  muscle  in  its  mechanical  effect.     In 


Fig.  40. — Lachrymal  and  Meibomian  glands.     (Sappey.) 

1,  1,  internal  wall  of  the  orbit  ;  2,  2,  internal  portion  of  the  orbicularis  palpebrarum  ;  3, 
3,  attachment  of  this  muscle  to  the  orbit ;  4,  orifice  for  the  passage  of  the  nasal 
artery  ;  5,  muscle  of  Horner ;  6,  6,  posterior  surface  of  the  eyelids,  with  the  Meibo- 
mian glands  ;  Y,  7,  8,  8,  9,  9,  10,  lachrymal  gland  and  ducts;  11,  11,  openings  of  the 
lachrymal  ducts. 


addition  to  this  anatomical  device,  the  alternating  pressure 
of  the  tendo  oculi  upon  the  lachrymal  sac  tends  to  act  as  a 
pump,  and  thus  to  draw  the  tears  from  the  globe  of  the  eye.'' 
The  flow  of  tears,  while  constant  in  a  state  of  health,  may 
be  greatly  increased  by  a  reflex  act.  Such  exciting  causes  as 
a  stimulation  of  the  nasal  mucous  membrane,  the  conjunc- 
tiva, the  optic  nerve,  and  the  tongue,  and,  more  forcibly,  the 
effect  of  the  emotions,  are  commonly  perceived.  It  is  said 
that  venous  congestion  of  the  liead  is  frequently  manifested 
by  an  excessive  production  of  tears."    The  different  efferent 


^  Hoffman  und  Schwald's  "  Bericht,"  1873. 

2  Darling  and  Ranney,  "  Essentials  of  Anatomy, 

2  Mich.  Foster,  op.  cit. 


1880. 


122 


THE  CRANIAL  NERVES, 


nerves,  which  exert  a  controlling  influence  upon  the  lachry- 
mal apparatus  in  response  to  the  exciting  causes  above  men- 
tioned, include  the  lachrymal  and  orbital  branches  of  the  fifth 
cranial  nerve  and  filaments  of  the  cervical  sympathetic' 

Many  of  the  facts  pertaining  to  the  optic  nerve  may,  by 
the  skillful  physician,  be  made  useful  in  his  daily  practice  as 
guides  to  diagnosis  ;  while  others  are  given  as  explanations 
of  many  phenomena  which  often  occa- 
sion alarm  to  those  not  familiar  with  the 
mechanism  of  their  production. 

CLINICAL   POINTS   APFORDED   BY   MEANS  OF 
THE   OPTIC   NERVE. 

The  optic  nerve  has  of  late  acquired 
an  importance  to  the  oculist,  which  is 
based  upon  the  physiological  distribution 
of  the  nerve,  but  which  has  to  the  spe- 
cialist more  than  a  theoretical  value, 
since,  by  means  of  the  knowledge  af- 
forded, the  diagnosis  of  the  existence  of 
cranial  tumors  pressing  upon  the  nerve, 
or  of  local  pressure  from  infiammatory 
exudations^  may  be  not  only  positively 
made  out,  but  the  exact  situation  of  the 
pressure  often  determined. 

The  hypotheses  of  WoUaston  and 
Mayo  have  been  so  far  confirmed  by  later 
investigators,  that  it  may  now  be  quite 
positively  stated  that  the  exact  half  of  each  retina  derives  its 
power  of  vision  from  one  optic  tract,  and  the  other  half  from 
the  opposite  tract.  It  has  been  proven  that  the  longitudinal 
fibers  of  each  optic  tract  supply  the  sense  of  vision  to  the 
outer  or  temporal  side  of  each  retina,  and  that  the  decussat- 
ing fibers  of  each  optic  tract  supply  the  inner  or  nasal  side 
of  each  retina.  When,  therefore,  the  optic  tract  of  either  side 
is  pressed  upon,  so  as  to  affect  the  entire  thickness  of  the 


Fig.  41. — Lachrymal  ca- 
nals^ lachrymal  sac, 
and  nasal  canal,  opened 
on  (heir  anterior  por- 
tion.    (Sappey.) 

1,  walls  of  the  lachrymal 
passages,  smooth  and 
adherent ;  2,  2,  walls 
of  the  lachrymal  sac, 
presenting  delicate 
folds  of  the  mucous 
membrane ;  3,  a  simi- 
lar fold  belonging  to 
the  nasal  mucous  mem- 
brane. 


'  See  experiments  of  Herzenstein,  Wolferz,  Reich,  and  others. 


VARIETIES  OF  HEMIANOPSIA.  123 

nerve,  and  thus  to  interfere  with  the  action  of  all  the  fibers 
which  that  tract  contains,  the  temporal  side  of  the  retina  of 
that  eye  which  corresponds  to  the  optic  tract  affected  and 
the  nasal  side  of  the  retina  of  the  opposite  eye  will  be  rendered 
blind,  or  will  be  impaired  in  exact  proportion  to  the  pressure 
exerted  upon  the  optic  tract.  Blindness  of  the  lateral  half  of 
the  retina  of  either  eye  is  termed  "  hemiopia"  or  "hemian- 
opsia" ;  and  this  condition  may  affect,  1,  both  eyes  simi- 
larly ;  2,  both  eyes  diametrically  ;  and  3,  either  eye  alone. 

When  either  eye  is  alone  affected  with  blindness  of  one 
half  of  the  retina,  it  indicates  that  the  optic  nerve  is  pressed 
upon,  or  otherwise  impaired,  at  a  point  situated  in  front  of 
the  optic  chiaswj ;  since,  if  the  optic  tract  were  the  seat  of  the 
existing  trouble,  both  eyes  would  be  affected,  as  it  would  be 
almost  impossible  for  the  pressure  to  affect  the  longitudinal 
fibers,  and  still  leave  the  decussating  fibers  of  the  tract  unin- 
jured, or  vice  versa.  With  this  as  a  starting  point  in  the 
diagnosis,  we  determine  which  half  of  the  eye  is  blind,  know- 
ing that,  if  the  nasal  side  be  the  one  where  vision  is  lost, 
the  pressure  must  be  on  the  inner  side  of  the  nerve,  and,  if 
the  outer  or  temporal  side  be  blind,  that  the  outer  side  of  the 
nerve  is  the  seat  of  the  disease  which  is  causing  the  pressure. 
Should  both  sides  of  one  eye  be  rendered  blind,  and  no  local 
cause  within  the  eye  be  found  to  exist,  then  the  existence  of 
pressure  anterior  to  the  optic  chiasm,  of  such  a  character  that 
the  entire  nerve  is  destroyed  or  impaired,  may  safely  be  diag- 
nosed. 

Total  amaurosis  of  one  eye  is  frequent  evidence  of  glioma 
or  sarcoma  within  the  orbit,  as  they  are  the  two  forms  of 
tumors  which  most  frequently  affect  that  region  ;  and  the 
diagnosis  of  the  presence  of  this  cause  will  probably  be  con- 
firmed, in  case  it  exists,  by  symptoms  referable  to  paralysis  of 
some  of  the  muscles  of  the  eye,  since  the  same  pressure  will 
be  also  likely  to  affect  either  the  third,  fourth,  or  sixth  nerves. 

The   most  common  form   of   "hemianopsia"'  met  with, 

^  A  synonym  for  hemiopia  in  its  generally  accepted  sense,  but  a  better  term,  smee  it 
means  blindness  of  half  of  the  retina,  while  the  former  means  only  half  vision. 


124  THE  CRANIAL  NERVES. 

as  the  result  of  the  pressure  of  cranial  tumors,  is  where  the 
temporal  half  of  one  eye  and  the  nasal  half  of  the  opposite 
eye  are  rendered  blind.  This  clinical  fact  is  supported  by  the 
anatomical  distribution  of  the  fibers  of  the  optic  tract,  which, 
as  before  stated,  supply  the  temporal  side  of  the  eye  of  the 
same  side  and  the  nasal  side  of  the  eye  of  the  side  opposite. 
When  this  condition  is  met,  we  know,  therefore,  that  the 
optic  tract  must  be  pressed  upon,  and  that  the  pressure  is 
being  exerted  upon  the  side  corresponding  with  the  eye  which 
is  blind  in  its  temporal  or  outer  half. 

In  those  uncommon  cases  where  the  inner  or  nasal  half  of 
each  retina  is  deprived  of  sight,  the  existence  of  pressure  at 
the  anterior  or  posterior  portions  of  the  optic  chiasm  may  be 
diagnosed,  since  the  decussating  fibers  of  each  optic  tract 
cross  each  other  at  these  points  only ;  and  the  nasal  side  of 
each  eye  being  affected  proves  that  the  decussating  fibers  of 
each  tract  must  be  simultaneously  pressed  upon,  without  any 
disturbance  of  the  longitudinal  fibers. 

In  those  cases  where  the  outer  or  temporal  sides  of  both 
retinae  exhibit  evidences  of  pressure  from  some  cause  within 
the  cranium,  the  explanation  of  the  mechanism  of  its  produc 
tion  has,  until  of  late,  been  involved  in  obscurity ;  but  it  is 
now  explained  by  a  curious  anatomical  relation  betyreen  the 
internal  carotid  arteries  (as  they  assist  to  foim  ''the  circle  of 
Willis")  and  the  optic  nerve.'  It  will  be  observed,  by  refer- 
ence to  the  plates  of  your  anatomy,  that  the  anterior  commu- 
nicating artery  passes  underneath  the  optic  nerves  and  in 
front  of  the  chiasm,  while  the  main  trunks  of  the  carotid 
arteries  are  adjacent  to  the  chiasm,  and  curl  outward  from 
nearly  its  central  point  toward  its  outer  edge.  Now,  in  senile 
degeneration  of  the  vessels,  the  atheromatous  changes  in  the 
arterial  coats  tend  to  destroy  the  elasticity  of  the  vessels,  and 
to  either  shorten  them,  or  to  render  them  less  elastic,  and 
thus,  in  this  region,  the  arteries  act  as  a  gathering  string- 
around  the  optic  chiasm,  and,  by  pressing  upon  the  outer  por- 
tion of  each  tract,  the  longitudinal  fibers  of  each  tract  are 

'  An  explanation  original,  I  believe,  with  Professor  H.  Knapp,  of  this  city. 


CAUSES  OF  HEMIANOPSIA. 


125 


impaired,  while  the  decussating  fibers  of  each  tract  are  not 
injured,  thus  accounting  for  the  blindness  of  the  temporal 
half  of  each  retina. ' 


Fig.  42. — A,  Longitudinal  fibers  of  the  optic  tract  (colored  red  on  chart) ;  B,  Decussat- 
ing fibers  of  optic  tract  (colored  blue  on  chart) ;  C,  Optic  Chiasm ;  D,  Eetina 
(showing  nerve  distribution  to  each  half) ;  E,  Optic  Nerves ;  F,  Optic  Tracts ; 
a' — b',  region  where  pressure  may  produce  "  hemianopsia  "  or  "  total  amaurosis  "  of 
one  eye;  e' — d,'  region  where  pressure  will  result  in  "hemianopsia"  of  opposite 
halves  of  the  retina  of  both  eyes ;  c' — c',  region  where  the  constriction  of  the  ves- 
sels of  the  "  circle  of  Willis  "  will  produce  "  hemianopsia "  of  temporal  half  of  the 
retina  of  both  eyes ;  b'  or  C,  special  localities  where  "  hemianopsia "  of  the  nasal 
half  of  the  retina  of  both  eyes  will  ensue  from  pressure;  C  c',  b  c',  region  which 
must  be  entirely  destroyed  by  pressure  to  produce  total  amaurosis  of  both  eyes. 

If  you  will  look  at  the  diagrammatic  picture  which  I  now 
show  you,  it  will  enable  you,  perhaps,  to  better  understand 
the  mechanical  explanations  of  the  various  conditions  which 
may  result  from  pressure  upon  the  optic  tracts,  or  upon  the 
optic  nerves,  if  in  front  of  the  chiasm.  You  will  perceive  that 
the-  longitudinal  fibers  of  each  tract,  which  I  have  colored 
red,"  if  traced  to  their  distribution,  supply  the  outer  half  of 
the  eye  of  the  same  side,  while  the  decussating  fibers  of  each 
tract,  which  I  have  colored  blue,'  pass  to  the  inner  or  nasal 

^  It  might  be  possible  for  two  tumors,  each  so  situated  as  to  affect  the  outer  side  only 
of  each  optic  tract,  to  produce  this  condition ;  but  the  probability  of  such  a  condition 
ever  existing  in  any  special  case  would  be  extremely  small. 

-  Shaded  dark  in  figure,  but  colored  for  class  demonstration. 

^  Not  colored  in  plate,  but  represented  by  decussating  lines.  The  presence  of  color 
for  demonstration  to  large  classes  is  oftentimes  of  great  assistance. 


126  THE  CRANIAL  NERVES. 

side  of  the  opposite  eye.  You  can,  therefore,  see  the  reason 
for  the  following  summary  of  the  guides  afforded  by  partial 
blindness  of  the  retina,  in  making  a  diagnosis  of  the  situation 
of  cranial  tumors. 

1.  Total  amaurosis  of  one  eye  indicates  pressure  between 
the  chiasm  and  the  eye  affected,  which  has  destroyed  the 
conducting  power  of  both  the  decussating  and  longitudinal 
fibers  of  the  nerve. 

2.  Total  amaurosis  of  both  eyes  seldom  occurs  in  tumor  ; ' 
but,  if  it  be  dependent  upon  a  tumor,  it  must  affect  the  chiasm 
itself,  and  have  completely  destroyed  it. 

3.  A  loss  of  vision  in  the  nasal  half  of  both  eyes  indicates 
the  existence  of  a  tumor,  either  in  front  of  or  behind  the  optic 
chiasm,  which  affects  only  the  decussating  fibers  of  each  tract. 

4.  A  loss  of  vision  in  the  nasal  half  of  one  eye  and  the 
temporal  half  of  the  other,  indicates  pressure  upon  the  optic 
tract  upon  the  side  where  the  temporal  half  of  the  retina  is 
destroyed. 

5.  A  loss  of  vision  in  the  temporal  half  of  both  eyes  indi- 
cates senile  degeneration  oi  the  vessels  forming  the  "circle 
of  Willis,"  which  are  creating  pressure  upon  the  outer  side  of 
each  of  the  optic  tracts. 

The  optic  nerve  may  be  the  guide  to  many  diseased  condi- 
tions of  parts  more  or  less  distant.  The  condition  of  hyper- 
esthesia of  the  retina,  to  which  its  terminal  filaments  are  dis- 
tributed, may  be  indicative  of  congestive  diseases  of  the 
brain  ;  of  the  development  of  cerebral  tumors  ;  and  of  certain 
mental  diseases  (as  prominently  shown  in  ecstasy,  hypo- 
chondria, etc.).  It  also  occurs  in  hysteria,  chorea,  chronic 
alcoholism,  narcotism,  the  inhalations  of  certain  toxic  gases, 
etc.  It  may  frequently  be  the  evidence  of  some  local  condi- 
tion of  the  optic  apparatus ;  hence  we  meet  it  in  >  cases  of 
congestive  and  inflammatory  conditions  of  the  retina ;  also 
where  an  excessive  amount  of  application  of  vision  has  been 
demanded,  in  disease  and  atrophy  of  the  nerve  itself,  and  in 
slight  compression  of  the  nerve  from  local  causes. 

*  This  condition  is  more  commonly  due  to  atrophy  of  the  optic  nerve  and  to  glaucoma. 


AMBLYOPIA  AND  AMAUROSIS.  127 

When  the  optic  nerve  filaments  become  ancesthetic,  sight 
is  impaired  in  the  exact  ratio  of  the  loss  of  sensibility  ;  hence 
we  speak  of  the  condition  of  "  amhlyopia^'^''  when  the  sight  is 
partly  destroyed  by  this  condition,  and  of  "  amaurosis  "  when 
the  sight  is  entirely  destroyed. 

We  may  consider  a  loss  of  sensibility  of  the  optic  nerve 
filaments  as  a  symptom  of  the  gravest  import,  since  it  indi- 
cates either  some  disease  of  the  brain  or  some  advanced 
changes  of  the  nerve  itself.  The  hi^ain  conditions  which  are 
most  liable  to  produce  this  condition  are  as  follows :  neuro- 
retinitis,  which  may  follow  cerebral  haemorrhage,  cerebral 
softening,  Bright' s  disease,  lead  poisoning,  and  syphilis;  the 
various  forms  of  ataxia ;  cerebral  tumors ;  chronic  effusion 
into  the  ventricles  ;  and  hysterical  cerebral  disorders. 

The  local  conditions  which  may  result  in  optic  anaesthesia 
include  inflammation  of  the  retina  and  the  adjoining  struc- 
tures ;  haemorrhage  into  the  retina  ;  retinal  tumors  ;  the  com- 
pression of  glaucoma ;  pressure  of  tumors,  in  the  orbit  or 
cranium,  upon  the  optic  tracts ;  thickening  of  the  meninges 
in  the  vicinity  of  the  optic  chiasm  ;  and  traumatism. 

Atrophy  and  sclerosis  of  the  corpora  geniculata  may  result 
in  amaurosis  ;'  lesions  of  the  cerebellum ""  may  be  accompanied 
by  symptoms  referable  to  the  optic  apparatus  (probably  on 
account  of  the  pressure  created  upon  adjoining  regions  of  the 
encephalon) ;  and  an  increase  of  intra-cranial  pressure,  from 
any  cause,  may  produce  retinal  changes. 

THE  THIRD   OR   "MOTOR   OOULI"   NERVE. 

This  nerve  has  its  apparent  origin  from  the  inner  border  of 
the  cms  cerebri.  The  deep  origin  of  the  nerve  can,  however, 
be  traced  to  the  "  locus  niger,'"  and  to  a  gray  nucleus  in  the 
floor  of  the  aqueduct  of  Sylvius,  slightly  below  the  tubercula 
quadrigemina. 

The  course  of  this  nerve,  after  it  escapes  from  the  brain,  is 
of  importance,  from  the  relations  which  it  has  with  impor- 

1  See  p.  58  of  this  volume.  ^  See  p.  62  of  this  volume. 


128 


THE  CRANIAL  NERVES. 


tant  structures,  and  from  the  physiological  phenomena  pro- 
duced by  it.  It  pierces  the  dura  mater  opposite  to  the  an- 
terior clinold  process,  in  order 
to  reach  the  outer  wall  of  the 
cavernous  sinus,  where  it  lies 
in  close  relation  with  the  fourth 
cranial  nerve,  and  the  ophthal- 
mic branch  of  the  fifth  cranial 
nerve,  being  above  them  both, 
and  also  with  the  cavernous 
sinus,  which  lies  internal  to  it. 
It  is  in  this  region  that  the 
nerve  is  joined  by  filaments 
from  the  cavernous  plexus  of 
the  sympathetic  system. 

The  nerve  now  passes  from 
the  cavity  of  the  cranium  by 
means  of  the  sphenoidal  fis- 
sure, having,  however,  divided 
into  two  branches,  before  its 
escape,  called  the  superior  and 
inferior. 

In  the  sphenoidal  fissure, 
these  two  branches  are  placed 
between  the  two  heads  of  the  external  rectus  muscle  of  the 
eyeball,  and  from  this  point  they  pass  onward  to  their  re- 
spective distributions,  viz.,  the  superior  branch  to  the  levator 
palpebrse  and  the  superior  rectus  muscles,  and  the  inferior 
branch  to  the  inferior  oblique,  the  inferior  rectus,  and  the  in- 
ternal rectus  muscles,  and,  by  a  small  filament,  furnishing  the 
motor  root  to  the  ciliary  or  lenticular  ganglion  of  the  orbit. 

The  third  cranial  nerve  thus  supplies  all  of  the  muscles  of 
the  eye  hut  two,  viz.,  the  superior  oblique  and  the  external 
rectus  muscles,  which  derive  their  motor  power,  respectively. 
from  the  fourth  and  the  sixth  nerves.  It  also  supplies 
filaments  to  the  ophthalmic  ganglion  (which  is  also  called 
the  ciliary,   and  the  lenticular    ganglion),   which  filaments 


Fig.  AZ.— Distribution  of  the  motor  oculi 
communis.     (Hirschfcld.) 

1,  trunk  of  the  motor  oculi  communis  ;  2, 
superior  branch ;  3,  filaments  which 
this  branch  sends  to  the  superior  rectus 
and  the  levator  palpebri  superioris  ;  4, 
branch  to  the  internal  rectus  ;  5,  branch 
to  the  inferior  recttbs  ;  6,  branch  to  the 
inferior  oblique  muscle  ;  V,  branch  to 
tJie  lenticular  ganglion  ;  8,  motor  oculi 
externus ;  9,  filaments  of  the  motor 
oculi  externus  anastomosing  with  the 
sympathetic ;  10,  ciliary  nerves. 


THE  MOTOR   OCULI  NERVE. 


129 


are  subsequently  distributed  to  the  ciliary  muscle  and  the 
iris. 

It  is  now  claimed  that  the  fibers  of  the  third  nerve,  which 
pass  to  the  aqueduct  of  Sylvius,  decussate ;  and  it  is  to  this 


IG... 


"^.       V 


Fig.  44. — Ciliary  mitscle  ;  magnijied  10  diameters,     (Sappey.) 

1,  1,  crystalline  lens;  2,  hyaloid  membrane;  3,  zone  of  Zinn;  4,  iris;  5,  5,  one  of  the 
ciliary  processes ;  6,  6,  radiating  fibers  of  the  ciliary  muscle ;  7,  section  of  the  circu- 
lar portion  of  the  ciliary  muscle ;  8,  venous  plexus  of  the  ciliary  process ;  9,  10, 
sclerotic  coat ;  11,  12,  cornea  ;  13,  epithelial  layer  of  the  cornea  ;  14,  membrane  of 
Descemet;  15,  ligamentum  iridis  pectinatum  ;  16,  epithelium  of  the  membrane  of 
Descemet;  17,  union  of  the  sclerotic  coat  with  the  cornea  ;  18,  section  of  the  canal 
of  Schlemm. 

anatomical  arrangement  of  its  fibers  of  origin  that  the  effect  of 
the  pupil  of  one  eye  upon  the  condition  of  the  pupil  of  the 
opposite  eye  is  occasionally  observed  in  disease,  and  that  the 
muscles  of  the  two  eyes,  as  well  as  the  iris,  are  thus  enabled  to 
work  in  perfect  harmony  with  each  other.  As  an  example  of 
this,  it  is  occasionally  observed  that,  when  amaurosis  affects 
one  eye,  the  pupil  of  the  diseased  organ  will  not  respond  to 
the  effect  of  light  upon  the  retina  of  that  side,  but,  when  the 


130 


THE  CRANIAL  NERVES. 


light  creates  a  movement  of  the  iris  of  the  unimpaired  eye, 
the  pupil  of  the  opposite  side  also  responds,  thus  showing 
that  reflex  action  is  possible  between  the  two  eyes. 


MECHANISM   OF  THE   CONTRACTION   OF   THE   PUPIL. 

The  mechanism  of  the  reflex  act,  by  which  the  third  nerve 
is  enabled  to  so  affect  the  contraction  and  dilatation  of  the 
pupil  as  to  have  its  varying  size  correspond  exactly  to  the 
requirements  of  the  retina,  as  regards  the  amount  of  light 


l  ^3    1^  ISlfi  1.  2„ 


Fig.  45. —  Choroid  coat  of  the  eye  and  the  ciliary  nerves.     (Sappey.) 

1,  optic  nerve ;  2,  2,  2,  2,  3,  3,  3,  4,  sclerotic  coat,  divided  and  turned  back  to  show  the 
choroid ;  5,  5,  6,  5,  the  cornea,  divided  into  four  portions  and  turned  back ;  6,  6, 
canal  of  Schlemm ;  7,  external  surface  of  the  choroid,  traversed  by  the  ciliary  nerves 
and  one  of  the  long  ciliary  arteries ;  8,  central  vessel  into  which  open  the  vasa  vorti- 
cosa ;  9,  9,  10, 10,  choroid  zone ;  11,11,  ciliary  nerves ;  12,  long  ciliary  artery ;  13,  1 3, 
13,  13,  anterior  ciliary  arteries ;  14,  iris  ;   15, 15,  vascular  circle  of  the  iris  ;  16,  pupil. 

necessary  for  perfect  vision  at  all  times  and  under  all  circum- 
stances, is  a  subject  of  interest  to  those  who  study  anatomy 
from  the  standpoint  of  its  physiological  bearings.  The  optic 
nerve,  when  a  person  comes  from  darkness  into  the  light, 
perceives,  on  account  of  the  dilated  condition  of  the  pupil, 
an  excess  of  light  which  at  once  compels  the  eye  to  momen- 
tarily close*  until  the  pupil  shall  become  contracted.     The 

*  A  reflex  act  produced  through  the  optic  nerve  upon  the  orbicularis  palpebrarum 
muscle. 


DISTRIBUTION  OF  THE  THIRD  NERVE. 


131 


sensation  of  over-stimulation  created  in  the  optic  nerve  by 
the  glare  of  light  entering  the  dilated  pupil  is  carried  back- 
ward to  the  brain,  and,  probably  in  the  region  of  the  aque- 
duct of  Sylvius,  creates  a  reflex  act  which  sends  motor  im- 
pulses along  the  fibers  of  the  third  nerve  to  the  iris,  by  means 
of  the  branch  to  the  ciliary  ganglion.  Thus  it  happens  that, 
when  the  eye  is  again  opened,  the  sensation  of  distress  in  the 
optic  nerve  is  no  longer  present,  and  the  pupil  is  found  to  be 
contracted  in  a  direct  proportion  to  the  amount  of  light  which 
at  the  time  exists. 

REASONS   FOR  THE   PECULIAR   DISTRIBUTIOK   OF   THE   THIRD   XERVE. 

The  distribution  of  the  third  cranial  nerve  may  suggest 
to  the  inquiring  mind  the  following  questions  :  ''Why  does 


Fig.  46. — Plexus  of  ciliary  nerves. — Nerves  of  the  iris.     (After  Sappey.) 

A,  choroid ;  B,  iris  ;  1,1,1,1,  ciliary  nerves  dividing  at  their  terminal  extremity  into  two 
or  more  branches,  which  anastomose  to  form  a  circular  plexus  surrounding  the  greater 
circumference  of  the  iris ;  2,  2,  plexus  formed  by  this  anastomosis ;  3,  3,  nerves  of 
the  iris  originating  from  this  plexus. 


iN'ature  use  three  nerves  to  control  the  movements  of  the  six 
ocular  muscles,  when  she  could  have  used  one  nerve  to  accom- 
plish the  effect?  Why  are  the  internal  rectus,  the  inferior 
oblique,  and  the  inferior  rectus  supplied  from  one  nerve 
source,  to  the  exclusion  of  the  external  rectus,  and  the  supe- 


132  THE  CRANIAL  NERVES. 

rior  oblique  muscles  ?  Furthermore,  why  is  the  iris  supplied 
with  nerve  power  from  the  third  nerve,  and  not  also  from  the 
fourth  nerve  or  the  sixth  nerve  ? " 

As  was  stated  in  the  introductory  lecture  of  this  course, 
when  touching  upon  the  distribution  of  nerves  in  general,  Na- 
ture often  indicates,  by  the  distribution  of  the  nerves,  some 
valuable  hints  as  to  the  physiology  of  the  parts  supplied 
by  each  nerve  filament ;  and  such  questions,  as  are  presup- 
posed above,  will,  if  constantly  asked  by  the  student  of  anat- 
omy, often  enable  him,  by  close  study,  to  gain  not  only 
information  of  a  most  practical  kind,  but  it  will  also  greatly 
assist  him  to  retain  in  his  memory  what  would  otherwise 
escape,  and  render  this  line  of  study  a  source  of  unceasing 
pleasure  and  interest. 

It  is  evident,  when  a  glance  at  the  distribution  of  the  mo- 
tor oculi  nerve  is  taken,  that  it  is  essentially  the  nerve  of 
accommodation  of  vision  for  objects  of  variable  distances 
from  the  retina.  By  its  control  over  the  internal  muscles  of 
the  orbit,  the  eyes  can  be  moved  in  unison  in  their  endeavor 
to  focus  objects  simultaneously  upon  each  retina,  and  thus  to 
gain  a  perception  of  the  solidity  of  objects,  which  can  not  be 
afforded  by  one  eye  alone.  It  is  a  fact,  which  perhaps  the 
reader  has  never  thought  of,  that  the  two  external  recti  mus- 
cles, or  the  two  superior  oblique  muscles,  are  seldom  called 
into  simultaneous  action,  since  they  both  tend  to  cause 
the  eye  to  roll  outward,  and  thus  oppose  the  natural  move- 
ment of  the  two  eyes,  one  of  which  usually  moves  inward 
while  the  other  moves  outward,  in  order  to  favor  the  percep- 
tion of  the  same  objects  by  the  retina  of  each  eye.  For  this 
reason  alone,  it  would  be  impossible  that  these  two  muscles 
of  each  orbit  should  be  supplied  from  the  same  nerve  as 
the  other  muscles,  since  they  could  not  possibly  act  in  har- 
mony with  each  other.  Again,  the  superior  oblique  and  the 
external  rectus  muscles  are  seldom  called  into  simultaneous 
action  except  in  oblique  movements  of  the  eye,  and  their 
actions  are  so  dissimilar  that  they  have  often  to  act  both  with 
and  without  the  aid  of  the  other ;   hence   two   nerves   (the 


ACCOMMODATION  OF  VISION. 


133 


fourth  and  sixth)  are  furnished  so  that  each  muscle  can 
have  its  own  source  of  nerve  supply. 

The  distribution  of  the  third  nerve  to  the  iris  affords  a  still 
more  beautiful  example  of  the  con- 
stant efforts  of  Nature  to  bring  all 
parts  into  a  harmony  with  each  oth- 
er, and  by  the  simplest  means  at 
her  control.  It  has  been  mentioned, 
in  connection  with  the  optic  nerve, 
that  the  pupil  contracts  as  the  eye 
is  drawn  inward,  and  also  in  at- 
tempts to  focus  near  objects  upon 
the  retina.  Now,  the  third  nerve 
is  the  nerve  by  which  not  only  is 
the  eye  drawn  inward,  but  it  is 
also  the  nerve  by  which  the  ciliary 
muscle  of  the  eye  is  enabled  to 
affect  the  cov/oexity  of  the  crystal- 
line lens  of  the  eye,  and  thus  to 
act  as  an  adjuster  of  the  focal  dis- 
tance of  objects  whose  images  fall 
upon  the  retina.     How  important 

it  is,  therefore,  that  the  pupil  which  is  so  essential  to  the 
proper  performance  of  vision,  since  it  controls  the  quantity 
of  light  admitted  to  the  retina,  should  be  placed  under  the 
same  nervous  control  as  the  muscles  of  accommodation  of 
vision  ! 

MECHANISM   OF  THE   DILATATION   OF  THE   PUPIL. 

The  pupil  is  made  to  dilate  by  means  of  muscular  fibers, 
which  radiate  from  the  margin  of  the  pupil  toward  the  cir- 
cumference of  the  iris.  It  is  probable  that  these  fibers  are 
under  the  control  of  the  sympathetic  system  ol  nerves.'  If 
so,  it  must  be  observed  that  the  sympathetic  nerves  have 
an  effect  upon  the  iris  directly  opposite  to  that  which  it 
exercises  upon  the  blood-vessels,    since,  when  it  is  stimu- 

^  Experiments  of  Julius  Budge,  1851,  and  Augustus  Waller,  "  Gazette  Medicale  de 
Paris."     Discovered  by  Petit,  1712. 
11 


Fig.    47. —  Ciliary    nerves^     course 
and  termination.   (After  Sappey.) 

1,  optic  nerve,  covered  by  its  exter- 
nal or  ligamentous  envelope; 
2,  optic  nerve,  covered  only  by 
its  proper  envelope  (neurilem- 
ma); 3,  3,  sclerotic,  or  fibrous 
envelope  of  the  eyeball :  4,  4, 
iris;  5,  pupil;  6,  6,  ciliary 
nerves  penetrating  the  scle- 
rotic ;  7,  7,  nerves  passing  be- 
tween sclerotic  and  choroid  ;  8, 
8,  plexus  resulting  from  their 
anastomoses  ;  9,  9,  ramifications 
extending  from  this  plexus  into 
the  iris. 


134 


THE  CRANIAL  NERVES. 


lated,  the  pupils  are  dilated,  while  the  blood-vessels  are  con- 
tracted. 

Mosso '  has  endeavored  to  show  a  relation  between  the  tur- 
gescence  of  the  vessels  of  the  iris  and  the  extent  of  dilatation 
of  the  pupil  which  exists  at  the  same  time,  and  thus  to  avoid 


Fig.  48. — Section  of  the  lens,  etc.,  showing  the  mechanism  of  accommodation.    (Fick.) 

The  left  side  of  the  figure  (F)  shows  the  lens  adapted  to  vision  at  infinite  distances  ;  the 
right  side  of  the  figure  {N)  shows  the  lens  adapted  to  the  vision  of  near  objects,  the 
ciliary  muscle  being  contracted  and  the  suspensory  ligament  of  the  lens  consequently 
relaxed. 


the  apparent  inconsistency  in  the  effect  of  the  sympathetic 
system  upon  the  same  type  of  muscular  structure. 

Oehl '  and  others  claim  that  the  sympathetic  fibers,  which 
act  in  antagonism  to  those  of  the  third  nerve  upon  the  iris, 
are  not  derived  from  the  ophthalmic  ganglion,  but  accompany 
the  ophthalmic  branch  of  the  fifth  cranial  nerve,  and  enter  the 
eye  with  the  long  ciliary  nerves  ;  and  that,  when  these  sympa- 
thetic filaments  are  divided,  stimulation  of  the  main  sympa- 
thetic cords  no  longer  causes  dilatation  of  the  pupil.  He  thus 
ascribes  to  the  fifth  cranial  nerve  the  power  of  dilating  the 
pupil,  and  regards  the  Gasserian  ganglion  as  the  source  from 
which  this  power  is  derived  from  the  sympathetic  system. 

The  experiments  of  Oehl  were  made  upon  dogs  and  rabbits, 
and  have  been  confirmed  by  Rosenthal,  Hensen,  Volckers, 
and  Yelpeau.  The  effect  of  these  fibers  of  the  fifth  nerve  is 
thought  by  these  observers  to  be  dependent  upon  a  vasa-mo- 
torial  influence  upon  the  blood  supply  of  the  iris. 


'  C.  F.  Mosso,  Turin,  1876. 


«  Henle  und  Meissner's  "  Bericht,"  1862. 


THE  MOVEMENTS  OF  THE  EYEBALL.  135 

Slight  oscillations  of  the  pupil  may  be  observed  to  occur 
synchronously  with  the  action  of  the  heart,  and  others,  also, 
wdth  the  respiratory  movements.  These  oscillations  have  been 
by  some  considered  as  an  evidence  that  the  movements  of  the 
pupil  were  the  result  of  alterations  in  its  vascularity,  the  iris 
contracting  when  its  vessels  are  filled,  and  dilating  when  its 
vessels  are  empty  ;  but  the  physiological  fact  that  the  move- 
ments of  contraction  and  dilatation  of  the  pupil  are  noticed  in 
the  bloodless  eye  seems  to  point  to  some  other  agency  than 
simply  an  alteration  in  the  blood  supply.' 

MOTIOKS   OF   THE   EYEBALL. 

Since  the  third  nerve  is  distributed  to  all  of  the  muscles 
of  the  eyeball  but  two,  the  motions  of  the  eye  are  largely 
controlled  by  it ;  while  accommodation  of  vision  is  also  pro- 
duced by  its  distribution  to  the  ciliary  muscle.  Some  prac- 
tical facts  may  be  here  noted  respecting  the  movements  of 
the  eyeball,  which  have  not  only  a  general  interest,  but  a 
diagnostic  value. 

The  eye  is  virtually  a  ball  placed  in  a  socket,  the  orbit 

^  "  The  impairment  of  iritic  reflex  action  ('  pupillary  reflex ')  was  first  intelligently 
studied  in  1869,  by  Dr.  Argyll  Robertson,  of  Edinburgh.  His  observations  have  since 
been  abundantly  verified  by  numerous  observers,  and  an  exhaustive  paper  on  the  subject 
has  been  published  by  Professor  W.  Erb,  of  Leipsic,  in  the  *  Archives  of  Medicine,'  Oc- 
tober, 1880.  Robertson,  and  others  after  him,  noticed  that  the  pupils  of  tabetic  patients 
did  not  dilate  in  the  shadow  and  contract  in  the  light,  as  do  normal  pupils,  and  they  fur- 
ther observed  that  during  the  effort  of  accommodation  there  occurred  a  normal  pupillary 
contraction.  In  other  words,  the  reflex  iris  movements  were  abolished,  while  its  associa- 
ted quasi-voluntary  movements  were  preserved.  These  phenomena  may  be  observed  in 
almost  all  patients  suffering  from  posterior  spinal  sclerosis,  and  I  am  in  the  habit  of  call- 
ing the  attention  of  students  to  the  symptom.  In  two  of  the  patients  now  under  my  care 
this  condition  is  not  present,  but  there  have  been  cases  of  abnormal  sclerosis  in  which  all 
the  symptoms  appeared  in  a  most  irregular  manner."    (E.  C.  Seguin,  "  Med.  Record,"  1881.) 

"  The  pupils  in  a  suspected  case  of  posterior-spinal  sclerosis  are  to  be  tested  in  the  fol- 
lowing manner :  the  patient  is  placed,  seated  or  standing,  facing  a  brightly  illuminated 
window,  and  told  to  keep  his  look  fixed  on  some  distant  object,  such  as  a  house  or  tree. 
By  alternately  closing  and  opening  the  lids,  or,  better,  by  shading  the  eyes  with  one's 
hand  momentarily,  it  is  easy  to  see  if  the  pupils  change  diameter.  It  is  of  the  utmost 
importance  that  the  patient's  intelligent  assistance  be  secured,  in  order  that  his  gaze  shall 
remain  adjusted  for  distance.  In  a  given  case  the  absence  of  reaction  to  light  having 
been  noted,  we  next  hold  up  one  finger  or  a  small  object  within  a  foot  of  the  patient's 
face,  and  bid  him  look  at  it.  At  once  the  pupils  contract,  and  do  so  in  proportion  to  the 
accommodative  effort  and  the  coincident  convergence.  When  the  patient  looks  at  the  dis- 
tant object,  and  relatively  or  absolutely  relaxes  his  accommodation,  the  pupils  dilate  again." 


136 


THE  CRANIAL  NERVES. 


and  the  globe  forming  a  ball-and-socket  joint.  In  its  socket 
joint,  the  eye  is  capable  of  a  variety  of  movements  ;  but  it  can 
not,  by  any  voluntary  effort,  be  moved  out  of  its  socket.  By 
disease,  however,  the  position  of  the  eyeball  within  the  cavity 


Fig.  49. — Muscles  of  the  eyeball.     (Sappey.) 

1,  attachment  of  the  tendon  connected  with  the  inferior  rectus,  internal  rectus,  and  ex- 
ternal rectus ;  2,  external  rectus,  divided  and  turned  downward  to  expose  the  inferior 
rectus ;  3,  internal  rectus ;  4,  inferior  rectus ;  5,  superior  rectus ;  6,  superior  oblique ; 
7,  pulley  and  reflected  portion  of  the  superior  oblique ;  8,  inferior  oblique ;  9,  levator 
palpebrae  superioris ;  10, 10,  middle  portion  of  the  levator  palpebne  superioris ;  11,  op- 
tic nerve. 


of  the  orbit  may  be  materially  altered.  By  pressure  on  the 
nerves  distributed  to  its  muscles,  paralysis  of  those  individual 
muscles  may  result  which  are  supplied  by  the  affected  nerve, 
and  the  eye  may  thus  be  deflected  from  its  normal  position 
by  the  other  muscles,  whose  motor  power  is  unimpaired.  The 
anatomical  fact,  that  the  muscles  which  move  the  eyeball  de- 
rive their  motor  power  from  three  sources,  viz.  :  the  third, 
fourth,  and  sixth  cranial  nerves,  may  often  be  made  a  means 
of  determining  the  situation  of  abnormal  conditions  within 
the  orbit  or  cranial  cavity,  by  a  thorough  familiarity  with  the 
points  of  origin  of  each  of  these  nerves,  and  the  relations 
which  each  bears  to  the  surrounding  parts  throughout  the 
whole  length  of  its  course. 


THE  MOVEMENTS   OF  THE  EYEBALL, 


137 


It  has  been  shown  by  Bonders  that,  though  we  can  move 
the  eye  in  almost  every  possible  variety  of  inclination,  we  can 
not,  by  a  voluntary  effort,  rotate  the  eyeball  around  its  longi- 
tudinal visual  axii^.  The  arrangement  of  the  muscles  of  the 
eyeball  would  seem  to  permit  of  such  a  movement,  but  we 
can  not  by  any  direct  effort  of  will  bring  it  about  by  itself, 
although  we  can  occasionally  produce  it  unconsciously  when 
we  endeavor  to  move  the  eyeballs  in  certain  special  directions. 

During  movements  of  the  head,  the  eyes,  if  directed  toward 
an  object,  may  be  kept  stationary  upon  that  object,  in  spite  of 
such  movements  of  the  head, '  very  much  as  the  needle  of  the 
ship's  compass  remains  stationary  when  the  ship  is  turned. 
By  this  wonderful  coordination  of  movement  steadiness  of 
vision  is  insured,  which  would  be  otherwise  impossible.^ 


Straight  movements.  \  To  depress  the  eye 


To  adduct  toward  the  nasal  side. 
To  adduct  toward  the  malar  side. 


Oblique  movements. 


A  TABLE   SHOWING  THE   ACTION-   OF  THE   OCULAR   MUSCLES. 

[  To  elevate  the  eye \  ^^f  ^«  «"Pf  ^^- 

f  Obliquus  mferior. 

I  Rectus  inferior. 

(  Obliquus  superior. 
Eectus  internus. 
Rectus  externus. 

r  Rectus  superior. 
To  elevate  and  adduct  the  eye )  Rectus  internus. 

(  Obliquus  inferior. 

r  Rectus  inferior. 
To  depress  and  adduct  the  eye }  Rectus  internus. 

'  Obliquus  superior. 

S'  Rectus  superior. 
Rectus  externns. 
Obliquus  inferior. 
I  Rectus  inferior. 

To  depress  and  abduct  the  eye )  Rectus  externus. 

(  Obliquus  superior. 

In  the  accompanying  table,'  in  which  the  various  motions 
of  the  eye  are  enumerated,  and  the  combinations  of  muscles 
necessary  to  produce  each  of  these  individual  motions  are 
shown,  it  will  be  perceived  that  in  the  straight  deflections  of 

'  An  effect  due  chiefly  to  the  action  of  the  oblique  muscles  of  the  eye. 
"^  Mich.  Foster,  "  Text-Book  of  Physiology." 
^  After  Mich.  Foster,  op.  cit. 


138  THE  CRANIAL  NERVES. 

the  globe  of  the  eye  never  more  than  two  muscles  are  required 
to  produce  them,  and  often  only  one ;  while,  in  the  oblique 
deflections  of  the  globe,  three  muscles  are  always  compelled 
to  work  in  unison.  It  may  furthermore  Ibe  stated  that,  to 
counterbalance  the  action  of  either  of  the  oblique  muscles  of 
the  eye,  two  muscles  are  always  required.  Suppose,  for  ex- 
ample, that  the  superior  oblique  muscle  of  the  orbit  was  para- 
lyzed from  pressure  upon  the  fourth  nerve,  the  eye  would 
then  be  drawn  downward  and  outward  only  by  the  combined 
action  of  the  external  and  inferior  recti  muscles,  although 
that  is  the  direct  line  of  action  of  the  muscle  paralyzed ;  while, 
if  that  muscle  should  contract,  and  thus  displace  the  eye 
downward  and  outward,  the  antagonistic  muscles  would  be 
the  superior  and  internal  recti  muscles,  since  the  former 
would  tend  to  draw  the  eye  upward  and  inward,  while  the 
latter  would  also  assist  in  drawing  the  eye  inward. 

The  ability  to  move  either  of  the  eyes  independently  of  the 
other  is  possessed  by  very  few  individuals,  although,  in  rare 
cases,  such  a  power  is  present.  The  movements  of  the  eye 
have  been  so  arranged  by  Nature  that  the  objects  seen  shall 
affect  the  corresponding  portions  of  each  of  the  two  retinae,  in 
order  to  insure  single  vision ;  and,  for  that  reason,  the  two 
eyes  will  be  perceived  to  move  exactly  alike,  each  passing 
simultaneously  to  the  left  or  to  the  right,  upward  or  down- 
ward. 

It  is  evident,  therefore,  when  we  throw  into  action  the 
rectus  internus  of  one  eye,  that  we  use  the  rectus  extemus  of 
the  opposite  eye,  and  vice  versa,  in  case  the  object  to  be  fo- 
cused upon  the  retinae  lies  away  from  the  median  line  of  the 
head  ;  but,  if  it  lies  in  the  direct  line  of  vision,  but  so  close  to 
the  face  as  to  require  a  muscular  effort  to  focus  it  upon  the 
retinae,  then  the  two  internal  recti  muscles  are  called  into 
simultaneous  action.  Finally,  in  case  the  object  to  be  per- 
ceived lies  at  a  distance  from  the  eyes,  it  becomes  necessary 
for  the  eyes  to  be  brought  into  nearly  a  condition  of  parallel- 
ism^ to  accomplish  which  the  two  external  recti  muscles  are 
called  into  simultaneous  action. 


CENTER  FOR   OCULAR  MOVEMENTS. 


139 


Such  a  complex  coordination  of  movement  as  the  various 
positions  of  the  eyes  demand  would  seem  to  indicate  that  a 
special  arrangement  had  been  made  within  the  component 
parts  of  the  brain  to  provide  for  its  control,  and  thus  insure 


rin£^' 


next.      Tsup.  r.int 
rum 

Fig.  50. — Diagram  showing  the  axes  of  rotation  of  the  eyeball.     (After  Fick.) 

The  black  lines  indicate  the  direction  of  the  power  applied  by  each  of  the  six  ocular  mus- 
cles. The  dotted  lines  indicate  the  axis  of  rotation  of  the  eyeball.  The  axis  of  rota- 
tion for  the  rectus  externus  and  rectus  internus  muscles,  being  perpendicular  to  the 
page,  can  not  be  shown  in  the  diagram. 

that  harmony  which  is  absolutely  required.  The  experiments 
of  Adamiik  '  tend  to  designate  the  tubercula  quadrigemina  as 
provided  with  distinct  centers,  which  control  certain  move- 
ments of  the  eyes.  Thus,  he  finds  in  tJie  nates  (the  upper 
portion  of  the  tubercula  quadrigemina)  a  common  center "  for 
both  eyes,  stimulation  of  the  right  side  producing  movements 
of  both  eyes  to  the  left,  of  the  left  side,  movements  to  the 
right ;  while  stimulation  of  the  middle  Hne,  behind,  causes  a 

'  Quoted  by  Flint,  Foster,  and  others. 

'  For  details  concerning  this  center,  see  page  58  of  this  volume. 


140  TEE  CRANIAL  NERVES. 

downward  movement  of  both  eyes,  with  a  convergence  of  the 
axes,  and,  if  made  in  front,  an  upward  movement  with  a  return 
to  parallelism,  both  of  which  effects  are  accompanied  by  the 
movements  of  the  pupil  naturally  associated  with  them. 

The  third  nerve  has  a  decided  importance  in  affording  us 
one  means  of  determining  the  distance  of  objects  from  the 
retinae  which  perceive  them,  viz.,  the  muscular  sense.  It  has 
been  previously  stated  that,  in  order  to  perceive  near  objects, 
the  internal  recti  and  the  ciliary  muscles  of  either  eye  are 
called  into  simultaneous  action,  and  we  soon  learn  to  uncon- 
sciously estimate  the  amount  of  muscular  power  required  to 
properly  adjust  the  eye  for  distinct  vision,  and  thus  to  use 
the  third  nerve,  as  well  as  the  optic  nerve,  as  a  guide  to  the  ac- 
curate determination  of  distance. 

ALTERATION    OF  THE   POSITION   OF   THE   HEAD   FROM    PARALYSIS   OF 
THE   OCULAR   MUSCLES. 

It  is  a  fact  well  known  among  oculists,  and  one  which 
often  helps  them  materially  in  diagnosis,  that  the  defects 
of  vision,  occasioned  by  impairment  in  the  power  of  some  of 
the  muscles,  which  control  the  eyeball,  cause  the  patients  un- 
consciously to  assume  a  position  of  the  head  which  tends  to 
assist  them  in  the  use  of  the  affected  eye.  So  diagnostic  are 
some  of  the  attitudes  assumed  by  this  class  of  afflicted  people, 
that  the  condition  which  exists  may  be  told  at  a  glance,  as 
the  patient  enters  a  room,  by  one  thoroughly  familiar  with 
the  diseases  of  this  important  organ.  The  explanation  of  this 
tendency,  on  the  part  of  this  class  of  patients,  lies  in  the  fact 
that  any  loss  of  power  in  the  ocular  muscles  immediately 
shows  itself  in  the  perception  of  every  object,  as  it  were, 
doubled;  and  it  is  to  overcome  these  double  iinages  that 
patients  almost  instantaneously  discover  their  ability  to  get 
rid  of  the  annoyance  by  some  special  attitude,  which,  of 
course,  depends  upon  the  muscle  which  is  weakened  or  para- 
lyzed. 

It  will  be  necessary,  in  order  to  make  you  clearly  under- 
stand the  mechanism  of  this  peculiarity,  that  the  separate 


ABNORMAL  ATTITUDE  FROM  OCULAR  PARESIS.        Ul 

action  of  the  six  muscles  which  directly  act  upon  the  globe  of 
the  eye  be  considered. 

The  action  of  each  of  the  ocular  muscles  may  be  given 
then,  as  follows,  with  the  proviso  that  many  of  the  motions 
of  the  eye  are  not  the  result  of  the  contraction  of  any  single 
muscle,  but  often  of  a  number  acting  either  in  unison  or  suc- 
cessively. 

The  superior  oblique  muscle  turns  the  eye  downward  and 
outward. 

The  inferior  oblique  muscle  turns  the  eye  upward  and 
outward. 

The  superior  rectus  muscle  turns  the  eye  upward  and 
inward. 

The  inferior  rectus  muscle  turns  the  eye  downward  and 
inward. 

The  internal  rectus  muscle  turns  the  eye  directly  inward. 

The  external  rectus  muscle  turns  the  eye  directly  outward. 

This  statement  as  to  the  above  muscles  reveals  nothing 
which  would  not  be  immediately  suggested  by  the  insertion 
of  each,  with  the  exception  of  the  superior  and  inferior  recti 
muscles,  which,  besides  the  action  which  their  situation 
would  naturally  suggest,  tend  also  to  draw  the  eyeball  in- 
ward^ on  account  of  the  obliquity  of  the  axis  of  the  orbit  and 
the  same  obliquity  of  the  muscles,  since  they  arise  at  the  apex 
of  the  orbit.  The  action  of  the  oblique  muscles  is,  as  any  one 
familiar  with  their  origin  and  insertion  would  naturally  sur- 
mise, to  control  the  oblique  movements  of  the  eyeball. 

Now,  as  soon  as  any  one  of  these  six  muscles  becomes 
pressed  upon  and  weakened  by  the  presence  of  tumors,  in- 
flammatory exudation,  syphilis,  or  other  causes,  the  patient 
at  once  perceives  double  images,  and,  in  order  to  get  his  eye 
into  such  a  relative  position  with  that  of  the  healthy  side  as 
to  enable  them  both  to  focus  upon  the  same  object  in  a  natu- 
ral manner,  the  patient  soon  learns  to  so  move  his  head  as  to 
compel  the  two  eyes  to  look  in  parallel  directions. 

A  very  simple  rule  can  be  suggested  by  which  you  may  be 
enabled,  not  only  to  tell  in  what  direction  a  patient  would  move 


142  THE  CRANIAL  NERVES. 

his  head  in  case  any  special  muscle  be  rendered  weak  or  utter- 
ly useless,  but  also  to  diagnose  the  muscle  affected,  when  you 
look  at  the  patient,  without  any  knowledge  of  his  history. 
The  rule  may  be  thus  stated :  In  paresis  of  any  of  the  ocu- 
lar muscles^  the  head  is  so  deflected  from  its  normal  posi- 
tion that  the  chin  is  carried  in  a  direction  corresponding  to 
the  action  of  the  affected  muscle. 

Thus,  in  paresis  of  the  external  rectus,'  the  chin  would  be 
carried  outward  toward  the  injured  muscle ;  while,  in  paresis 
of  the  internal  rectus  muscle,  the  head  would  be  turned  away 
from  the  side  on  which  the  muscle  fails  to  act.  In  case  the 
superior  oblique  muscle  is  impaired,  the  chin  would  be  carried 
downward  and  outward ;  while,  in  the  case  of  the  inferior 
oblique  muscle,  the  chin  would  have  to  be  moved  upward 
and  outward  to  benefit  the  vision  of  the  patient.  The.  supe- 
rior and  inferior  recti  muscles,  when  impaired  by  disease  or 
other  causes,  would  likewise  create  a  deflection  of  the  head  in 
a  line  corresponding  to  that  of  their  respective  actions. 

CLINICAL   POINTS   OF   INTEREST    PERTAINING   TO   THE   THIRD   NERVE. 

Paresis  of  the  external  and  internal  recti  muscles  causes,  in 
addition  to  the  facts  already  described,  another  point  of  very 
great  value  in  diagnosis,  viz.,  an  alteration  in  the  apparent 
size  of  the  objects  seen  from  what  they  would  be  in  health. 
The  condition  of  vision,  termed  by  oculists  " megalopsia^^  or 
'-'- macropsia^^'^  signifies  paresis  of  the  external  rectus;  while 
the  opposite  condition,  called  "m^croJ!?5^a,"  indicates  loss  of 
power  in  the  internal  rectus  muscle. 

In  the  former  of  these  conditions,  the  objects  seen  by  the 
patient  seem  to  be  greater  in  point  of  size  than  the  intelligence 
of  the  patient  assures  him  is  the  case ;  while,  in  the  latter, 
objects  seem  smaller  to  the  patient  than  they  really  are. 

To  explain  to  you  just  how  these  variations  of  vision  are 

'  While  this  statement  would  be  absolutely  true  in  theory  in  all  cases,  we  must 
acknowledge,  as  a  clinical  fact,  that  patients  leam  to  utterly  disregard  the  image  in  the 
affected  eye,  when  the  internal  or  external  rectus  is  the  scat  of  paresis,  and  to  use  the  nor- 
mal eye  only  for  the  purposes  of  vision,  thus  rendering  this  attitude  of  the  head  less  diag- 
nostic than  when  the  oblique  muscles  are  affected. 


MEGALOPSIA    AND  MICROPSIA.  I43 

accomplished  may  require  a  more  extended  discussion  of  the 
physiological  problems  of  vision  than  an  anatomical  discus- 
sion can  properly  deal  with  ;  but,  to  understand  it,  you  must 
know  that  the  apparent  size  of  any  object  depends  upon 
the  ability  of  the  person  to  properly  and  accurately  appreci- 
ate the  angle  formed  between  rays  of  light  coming  from  the 
object  and  entering  the  pupils  of  each  eye,  or,  in  other  words, 
the  distance  at  which  the  object  is  placed  from  the  retina. 
Now,  in  the  case  of  paresis  of  the  external  rectus  muscle,  the 
object  is  caused  to  appear  nearer  to  the  eye  than  it  really  is, 
and  thus  to  be  larger  than  normal  vision  would  cause  it  to 
seem,  since  the  angle  of  the  axes  of  vision  is  greater  ;  while, 
in  case  of  the  paralysis  of  the  internal  oblique,  the  object  is 
apparently  much  farther  removed  from  the  eye  than  it  really 
is,  and  thus  the  intelligence  construes  it  as  of  smaller  size  than 
it  would  if  the  visual  perceptions  were  normal. 

There  is  only  one  other  condition  of  the  eye  where  the  size 
of  objects  perceived  by  the  retina  is  either  increased  or  mark- 
edly diminished,  if  the  actual  size  be  taken  as  a  standard  of 
measurement,  and  this  condition  is  one  of  inflammation  of  the 
choroid  coat  of  the  eye.  It  is  a  well-recognized  fact  that,  in 
the  effusive  form  of  choroiditis,  objects  are  perceived  as  much 
smaller  than  they  really  are,  while  in  cicatricial  choroiditis 
the  size  of  the  object  is  magnified. 

These  phenomena  can  not  be  explained  as  the  result  of  a 
change  in  the  angle  of  the  axis  of  vision,  since  nothing  exists 
to  disturb  the  perception  of  distance  ;  but  it  is  attributed  to  a 
separation,  in  the  one  case,  and  to  an  aggregation  in  the 
other,  of  the  cones  of  the  retina. 

The  eye,  by  constant  use,  has  become  enabled  to  partly 
estimate  the  size  of  objects  by  the  number  of  cones  in  the 
retina  w^hich  are  covered  by  the  image  of  the  object.  Thus, 
when,  from  causes  such  as  have  been  mentioned  above,  the 
elements  of  the  retina  are  either  huddled  more  closely  to- 
gether by  a  cicatrix  of  the  choroid  coat  of  the  eye,  or  dissem- 
inated over  a  larger  space  than  they  normally  occupy  by  an 
effusion  of  the  choroid  coat,  the  number  of  cones  covered  by 


144 


THE  CRAMAL  NERVES. 


the  image  thrown  upon  the  retina  is  either  increased,  thus 
apparently  magnifying  the  size  of  the  object,  or  the  number 
of  cones  affected  is  decreased,  and  thus  the  size  of  the  object 
seen  is  apparently  diminished. 


Fig.  51. — A.  Vertical  section  of  tJie  retina.     B.   Connection  of  the  rods  and  cones  of 
(H.  Miiller.)  the  retina  with  the  nervoits  elements. 

(Sappey.) 

A.  1,  1,  layer  of  rods  and  cones;  2,  rods;  3,  cones;  4,  4.  5,  6,  external  granule  layer; 

7,  inter-granule  layer  (cone-fiber  plexus);  8,  internal  granule  layer;  9,  10,  finclv 
granular  gray  layer;  11,  layer  of  nerve  cells;  12,  12,  12,  12,  14,  14,  fibers  of  tin 
optic  nerve  ;  13,  membrana  Hmitans. 

B.  1,  1,  2,  3,  rods  and  cones,  front  view;  4,  R,  6.  rods,  side  view;  7,  7,  8,  8,  cells  of 

the  external  and  internal  granule  layers ;  9,  cell,  connected  by  a  filament  with  sub- 
jacent cells;  10,  13,  nerve  cells,  connected  with  cells  of  the  granule  layers;  11,  21, 
filaments  connecting  cells  of  the  external  and  internal  granule  layers  (12  is  not  in 
the  figure);  14,  15,  16,  17,  18,  19,  20,  22,  23,  24,  25,  26,  a  rod  and  a  cone,  con- 
nected with  the  cells  of  the  granule  layers,  with  the  nerve  cells,  and  with  the  nerve 
fibers. 


In  cases  where  complete  blindness,  even  to  the  sensation 
of  light,  exists,  as  sometimes  occurs  in  amaurosis, '  the  eyes 

'  For  the  causes  of  this  condition,  see  page  127  of  this  volume. 


PARALYSIS  OF  THE  THIRD  NERVE.  I45 

remain  fixed  and  immovable,  gazing  steadily  forward,  even 
when  objects  are  made  to  pass  before  tHe  vision  ;  while  in 
cases  of  partial  blindness,  which  prevent  the  perception  of 
outline,  but  still  allow  of  the  perception  of  passing  objects 
between  the  light  and  the  retinae,  by  the  shadow  which  they 
throw,  the  eye  involuntarily  moves  in  a  direction  which  cor- 
responds to  that  of  the  moving  object. 

Cases  in  which  the  third  nerve  has  been  impaired  by  pres- 
sure or  disease,  or  totally  destroyed  by  section,  are  character- 
ized by  a  falling  of  the  upper  eyelid  over  the  pupil,'  and  an 
inability  to  raise  it,  owing  to  the  inaction  of  its  levator  mus- 
cle, so  that  the  eye  appears  constantly  half  shut.  This  con- 
dition is  known  by  the  name  of  "ptosis.'^''  The  movements 
of  the  eyeball  are  also  nearly  suspended,  and  permanent  ex- 
ternal strabismus  takes  place,  owing  to  the  paralysis  of  the 
internal  rectus  muscle,  while  the  external  rectus,  animated  by 
a  different  nerve,  preserves  its  activity.  From  paralysis  of 
the  fibers  distributed  to  the  iris,  a  dilatation  of  the  pupil  is 
also  produced,  and  accommodation  of  the  injured  eye  for  near 
objects  is  no  longer  performed. 

While  the  upper  eyelid  is  partially  raised  by  the  levator 
palpebrse  muscle,  which  is  supplied  by  the  third  nerve,  it  is 
also  raised  by  means  of  muscular  fibers,  which  are  governed 
by  the  cervical  sympathetic.  A  similar  set  of  fibers  exists  in 
the  lower  eyelid,  and  is  governed  by  the  same  nerves  ;  and  it 
is  probably  through  the  influence  of  the  sympatJietic  system 
that  the  eye  is  opened.  In  the  act  of  wdnking,  where  the 
shutting  of  the  eye  is  usually  affected  more  rapidly  than  the 
opening,  a  contrast  is  afforded  between  the  action  of  the  cra- 
nial nerves  and  those  of  the  sympathetic,  since  closing  of  the 
eye  is  performed  by  the  facial  nerve." 

External  strabismus  may  often  occur  without  the  condi- 
tion of  ''ptosis"  being  present,  the  filament  to  the  levator 
palpebrse  muscle  not  being  affected. 

When  all  the  muscles  supplied  by  the  third  nerve  are 

^  So  marked  is  this  deformity  that  the  upper  lid  frequently  almost  touches  the 
lower  lid.  ^  'M\c\i.  Foster,  op.  cit. 


146  THE  CRANIAL  NERVES. 

paralyzed,  the  globe  of  the  eye  is  slightly  protruded,  from 
relaxation  of  most  of  its  muscles. 

In  strabismus,  or  squint,  an  optical  defect'  is  usually 
present.  So  large  is  the  percentage  of  optical  error  in  those 
cases  where  the  eyes  turn  inward  toward  the  nose,  that  this 
condition  seldom  exists  without  an  accompanying  hyperopia 
or  far-sightedness,  due  to  a  diminution  of  the  antero-posterior 
axis  of  the  eye  ;  while  in  external  squint,  where  the  eye  looks 
away  from  the  nose,  the  opposite  condition  of  myopia,  or 
near-sightedness,  is  often  present,  but  perhaps  not  in  as  large 
a  percentage  of  cases  as  in  the  opposite  deflection  of  the  eye. 
For  this  reason,  operations  are  often  of  little  benefit  when 
performed  for  the  relief  of  strabismus,  unless  the  error  in 
vision  is  accurately  determined  and  corrected  by  the  appro- 
priate lenses. 

DISEASES   OF  THE   OCULAR   MUSCLES   AND  THEIR   CAUSES. 

The  muscles  of  the  orbit  may  present  the  conditions  of 
spasm,  contracture,  motor  irritation,  or  paralysis. 

The  condition  of  "  nystagmus  "  is  characterized  by  clonic 
spasm  of  the  external  ocular  muscles,  and  by  peculiar  oscilla- 
tions or  involuntary  movements  of  the  organ.  It  is  always  a 
bilateral  affection,  and  its  starting-point,  according  to  the  ex- 
periments of  Adamuk  and  Ferrier,"  seems  to  be  situated  within 

^  See  Haynes  Walton,  Stellwag,  and  others.  In  speaking  of  this  optical  defect,  depen- 
dent upon  simple  hyperopia,  Dr.  Loring  says,  in  an  article  previously  quoted  in  this  vol- 
ume :  "  I  have  known  boys  of  eight  or  ten  years  of  age  to  beg  their  parents  to  let  them 
undergo  the  pain  of  an  operation  to  rid  themselves  of  a  deformity  which  subjects  them  so 
often  to  the  unfeeling  remarks  of  their  elders,  usually  friends  of  the  family,  as  well  a 
the  uneuphonious  but  expressive  titles  bestowed  upon  them  by  their  own  contemporaries, 
of  goggle-eye  and  cock-eye.  Nor  does  this  end  with  childhood.  The  deformity  is  a  dis- 
advantage to  him  through  life.  It  pursues  him  in  his  business  and  in  his  profession. 
Cheated  of  feature  by  dissembling  nature,  he  is  often  thought  to  be  dissembling  himself, 
when  nothing  is  further  from  his  thoughts.  How  often  do  we  hear  people  say  of  another, 
whom  we  know  to  be  perfectly  upright  and  trustworthy,  that  they  do  not  like  him  because 
he  never  looks  them  squarely  in  the  face !  And  it  is  a  little  curious  that  precisely  here  it 
is  that  the  lesser  degrees  of  the  trouble  produce  the  most  effect.  That  peculiar  expression 
which  people  complain  so  much  of  is  generally  due  to  a  deviation  in  the  axes  of  the  eyes 
— a  slight  convergence,  which  is  never  very  conspicuous,  and  at  times  only  to  be  detected 
by  a  trained  eye,  but  which,  nevertheless,  produces  in  all  a  very  disagreeable  impression, 
although  not  marked  enough  to  betray  its  cause. 

'  See  page  68  of  this  volume. 


CAUSES  OF  PARALYSIS  OF  THE  THIRD  NERVE.        147 

the  anterior  tubercula  quadrigemina.  It  may  be  produced  by 
causes  affecting  either  the  central  nerve  ganglia,  the  periphe- 
ral nerves,  the  refracting  media  of  the  eye,  or  the  retina.  We 
thus  find  it  existing  in  connection  with  meningitis,  hydro- 
cephalus, etc.,  in  uterine  diseases,  worms,  dentition,  caries 
of  the  teeth,  etc.,  and  in  some  of  the  diseases  of  the  eye  or 
optic  nerve. 

Spasm  of  the  fibers  of  the  iris  is  observed,  in  rare  cases,  to 
exist  in  connection  with  some  irritative  condition  of  the  cere- 
bro-spinal  system,  which  has  involved  the  cilio-spinal  center 
of  the  spinal  cord.' 

By  contracture  of  a  muscle  is  meant  a  permanent  shorten- 
ing, in  contrast  to  its  temporary  shortening  when  under  the 
ordinary  influence  of  the  motor  stimulus.  It  occurs,  in  the 
ocular  group  of  muscles,  as  the  result  of  the  direct  irritation 
following  some  pathological  process,  at  a  seat  more  or  less 
distant  from  the  orbit ;  or  as  the  effect  of  prolonged  paralysis 
of  some  of  the  antagonistic  muscles. 

In  those  cerebral  and  spinal  conditions  in  which  convulsive 
attacks  are  produced,  and  in  attacks  of  hysteria,  the  evidences 
of  well-marked  motor  irritation  of  the  ocular  muscles  are 
often  observed. 

Paralysis  of  the  ocular  group  of  muscles  may  vary  in 
degree,  thus  constituting  either  paresis  or  true  paralysis  ;  also 
in  extent,  thus  affecting  all  the  muscles  supplied  by  the  third 
nerve,  and  often  the  fourth  and  sixth  nerves  as  well,  or,  again, 
only  separate  muscles  ;  and  finally  in  duration  and  its  sus- 
ceptibility to  treatment.  This  symptom  may  be  either  an 
initial  symptom,  or  a  complication  of  some  central  disease,  or 
the  result  of  peripheral  causes. 

Paralysis  of  the  muscles  supplied  by  the  third  nerve  is 
most  frequently  produced  by  the  following  causes  :  Circum- 
scribed meningeal  processes  at  the  base  of  the  skull ;  tu- 
mors, softening,  and  haemorrhage  of  the  cerebral  peduncles ; 
softening  and  haemorrhage  of  the  cerebral  ganglia ;   syphi- 

'  For  details  as  to  the  situation  and  function  of  this  center,  the  reader  is  referred  to 
subsequent  pages  of  this  volume. 


148  THE  CRANIAL  NERVES, 

lis  (affecting  the  cranial  or  orbital  cavity)  ;  orbital  tumors ; 
diphtheria  ;  and,  finally,  aneurisms  of  the  carotid  (as  reported 
by  Lebert ').  In  the  development  of  ataxia^  the  third  nerve 
may  become  paralyzed  simultaneously  with  other  nerves  of  the 
cranium,  or,  possibly,  without  other  nerves  being  affected, 
and  the  same  condition  may  follow  the  prolonged  use  of  co- 
nium  or  gelsemium. 

When  the  paralysis  of  the  third  nerve  is  produced  by  intra- 
cranial lesions,  the  paralysis  is  liable  to  be  bilateral  or  to  tend 
toward  a  symmetrical  development  as  the  disease  progresses ; 
while  the  fourth  and  sixth  nerves  are  often  subsequently  af- 
fected. There  are  also  other  symptoms,  of  great  value  in 
deciding  upon  the  existence  of  intra- cerebral  disease,  which 
may  be  present,  such  as  the  coexistence  of  cephalalgia,  ver- 
tigo, symptoms  of  neuro-retinitis,  disturbances  of  speech  and 
of  the  intellectual  faculties,  convulsive  movements  of  a  local 
or  general  type,  a  sense  of  weight  in  the  limbs,  or,  possibly, 
the  presence  of  paresis  or  paralysis  of  the  muscles  of  the 
extremities. 

''  A  very  large  proportion  of  tabetic  patients  tell  of  past  or 
present  diplopia,  and,  in  a  certain  number  of  cases,  the  ocular 
paralysis  precedes  the  pains  and  ataxia  by  several  years.  So 
true  is  this  statement,  that  it  has  become  an  established  prac- 
tice with  neurologists  and  ophthalmologists  to  suspect  poste- 
rior spinal  sclerosis  in  adults  who  present  themselves  with 
strabismus,  diplopia,  or  ptosis.  In  such  a  case  we  should 
carefully  question  the  patient  about  the  occurrence  of  fulgu- 
rating pains,  and  test  the  pupillary  and  tendinous  reflexes.  I 
need  hardly  add  that  another  obligatoiy  line  of  inquiry  in 
such  cases  is  with  reference  to  symptoms  of  syphilis."  ' 

The  same  remarks  apply  to  atrophy  of  the  optic  nerve, 
which  is  occasionally  an  early  symptom. 

It  is  not  infrequent  for  lesions  of  the  spinal  cord  to  pro- 
duce paralysis  of  the  ocular  muscles.  The  presence  of  such 
an  exciting  cause  may  be  surmised  by  the  coexistence  of  vague 
neuralgias  in  the  branches  of  the  cervical  or  brachial  plexuses, 

'  Quoted  by  Rosenthal.  «  E.  C.  Seguin,  "  Med.  Record,"  1881. 


THE  FOURTH  C RACIAL  NERVE.  I49 

or  in  the  sciatic  nerves  ;  of  abnormal  sensations  in  tlie  back, 
knees,  and  soles  of  the  feet ;  seminal  emissions,  frequent  or 
prolonged  erections,  or  diminished  sexual  power;  extreme 
sensitiveness  to  moisture  of  the  atmosphere  or  winds ;  a 
tendency  to  fatigue,  often  present  after  a  night's  repose; 
and  an  increase  in  the  galvano-excitability  of  the  main  nerve 
trunks. 

Paralysis  of  the  ocular  muscles  may  accompany  glosso- 
lahio-pTiaryngeal  paralysis  (Duchenne's  disease'),  if  the  cen- 
ter for  the  movements  of  the  eye  be  affected  at  the  same  time 
as  the  centers  of  the  muscles  of  speech  and  deglutition ;  in 
this  case,  the  third  and  sixth  nerves  are  frequently  affected 
simultaneously.  The  same  condition  of  the  ocular  muscles 
may  also  accompany  ataxic  symptoms  of  cerebral  origin. 

Rheumatism  may  produce  ocular  paralysis.  This  cause  is 
to  be  suspected  w^hen  no  symptoms  exist  which  seem  to  point 
to  local  trouble  in  the  orbit  or  brain.  It  is  found  to  affect  the 
motor  oculi  and  the  abducens  nerves  more  frequently  than  the 
patheticus. 

Diplopia  and  strabismus  are  often  the  first  symptoms  of 
ceiebral  diseases  or  ataxia,  since  they  may  appear  before  the 
other  parts  of  the  muscular  system  are  affected.  If  they  show, 
at  times,  a  tendency  toward  spontaneous  retrogression,  and 
again  return  with  the  simultaneous  occurrence  of  neuralgic 
pain,  the  development  of  a  cerebral  lesion  is  rendered  still 
more  probable. 


THE  FOURTH   (TROCHLEAR   OR  PATHETIC)    NERVE. 

The  apparent  origin  of  this  nerve  is  from  the  superior 
peduncle  of  the  cerebellum^  and  it  then  winds  around  it,  pass- 
ing close  to  the  posterior  border  of  the  pons  Varolii.  The 
deep  origin  of  the  fibers  may  be  traced  to  four  different  sit- 
uations, as  follows :   1,  some  fibers  to  the  substance  of  the 

'  The  symptoms  of  this  condition  will  be  found  mentioned  in  more  detail  in  connec- 
tion with  the  hypo-glossal  nerve. 
12 


150 


THE  CRANIAL  NERVES. 


peduncle ;  2,  other  fibers  to  the  valve  of  Vienssens,  where 
they  are  lost,  with  the  exception  of  a  few,  which  can  be  traced 
to  the  frenulum ;  3,  a  few  fibers  to  the  tuhercula  quadrige- 
mina ;  4,  a  large  bundle,  which  pass  inward  toward  the 
median  line  and  then  decussate  with  corresponding  filaments 
of  the  opposite  side. 

This  decussation  of  the  fibers  of  the  nerve  is  for  the  same 
physiological  reason,  as  was  mentioned  in  connection  with  the 

preceding  nerve,  viz.,  to  afford 
harmony  of  action  between 
the  two  sides,  when  the  eyes 
are  compelled  to  remain  fixed 
upon  an  object  during  move- 
ments of  the  head. 

From  the  point  of  appar- 
ent origin,  the  nerve  passes 
forward  along  the  outer  wall 
of  the  cavernous  sinus,  where 
it  lies  Ijelow  the  third  nerve 
and  above  the  ophthalmic 
branch  of  fhe  fifth  nerve^  and 
escapes  from  the  cavity  of  the 
cranium,  through  the  highest 
part  of  the  sphenoidal  fissure, 
into  the  cavity  of  the  orbit. 
The  question  of  the  func- 


FiG.  52. — Distnbution  of  Ihe  patheticus. 
(Hirschfeld.) 
I,  olfactory  nerve ;  II,  optic  nerves ;  III,  mo- 
tor oculi  communis ;  IV,  paihdicus,  bi/  iJie 
side  of  the  ophthalmic  branch  ofthejifth^ 
and  passing  to  the  superior  oblique  muscle; 
VI,  motor  oculi  cxternus  ;  1,  ganglion  of 
Gasscr;  2,  3,  4,  5,  6,  7,  8,  9,  10,  ophthal- 
mic division  of  the  fifth  nerve,  with  its 
branches. 


tion  of  this  nerve  resolves  it- 
self simply  into  the  mode  of  action  of  the  superior  oblique 
muscle.  This  muscle  arises  just  above  the  inner  margin  of 
the  optic  foramen,  and  passes  forward  along  the  upper  wall 
of  the  orbit,  at  its  inner  angle,  to  a  little  cartilaginous  ring, 
which  serves  as  a  pulley  for  its  tendon.  Its  tendon  becomes 
rounded  just  before  it  passes  through  this  ring,  where  it  makes 
a  sharp  curve,  passes  outward  and  slightly  backward,  and  be- 
comes spi-ead  out,  to  be  attached  to  the  globe,  at  the  superior 
and  external  part  of  its  posterior  hemisphere.  It  is,  there- 
fore, the  direct  antagonist  of  the  inferior  oblique  muscle. 


THE  FIFTH  CRANIAL  NERVE.  15^ 

In  its  function,  it  is  purely  a  motor  nerve,  but  it  receives 
a  few  recurrent  fibers  from  the  fifth  nerve,  which  are  sen- 
sory. 

AVhen  this  nerve  is  paralyzed,  the  position  of  the  eye 
shows  no  apparent  change,  except  when  the  head  is  moved 
from  side  to  side,  in  which  case  the  eye  moves  loitli  the  liead ; 
the  absence  of  the  usual  compensating  movement  of  the  eye, 
which  accompanies  all  the  movements  of  the  head,  being  de- 
stroyed in  consequence  of  the  paralysis  of  the  superior  oblique 
muscle,  which  greatly  assists  in  this  act.  The  patient  also 
sees  a  double  image,  whenever  attempts  are  made  to  look 
straight  forward,  or  at  objects  situated  toward  the  paralyzed 
side ;  but  the  image  becomes  a  single  one  when  the  head  is 
turned  toward  the  sound  side  to  view  any  object ;  hence  this 
abnormality  of  attitude  of  the  head  is  usually  present/ 


THE  TKIGEMINUS  OE  FIFTH  NERVE. 

This  important  nerve  has  its  apparent  origin  within  the 
cranium  from  the  lateral  aspect  of  ih.Qjpons  Varolii,  although 
its  deep  fibers  have  been  traced  by  Lockhart  Clarke  to  two 
distinct  nuclei,  situated  in  the  floor  of  the  fourth  mntricle 
near  to  the  gray  tubercle  of  Rolando.''  It  is  a  mixed  nerve, 
having  a  distinct  motor  and  sensory  root ;  and  thus  pos- 
sesses both  afferent  fibers,  through  which  sensory  impres- 
sions are  transmitted  to  the  brain,  and  efferent  fibers,  by 
which  motor  impulses  are  transmitted  from  the  brain  to  the 
periphery  of  some  branches  of  the  nerve. 

The  intimate  relations  which  the  nerve  bears  with  the 
points  of  origin  of  the  sixth,  seventh,  eighth,  ninth,  tenth, 
eleventh,  and  twelfth  cranial  nerves  in  the  floor  of  the  fourth 
ventricle  possibly  explain  many  of  those  phenomena  which 
are  considered  as  reflex  in  character,  and  whose  starting-point 

^  For  other  examples  of  this  diagnostic  guide  in  paralysis  of  ocular  muscles,  sec  pre- 
vious pages  upon  the  third  cranial  nerve. 

-  See  pages  which  relate  to  the  medulla  oblongata. 


152 


THE  CRANIAL  NERVES. 


seems  to  depend  upon  some  irritation  of  the  fifth  nerve  by- 
means  of  various  branches. 

The  two  roots  of  this  nerve  pass  forward,  side  by  side, 
as  far  as  the  petrous  portion  of  the  temporal  bone.     At  this ' 
point  a  marked  enlargement,  called  the  ganglion  of  Gasser,  is 
developed  upon  the  sensory  root ;  and  subsequently  this  root] 


Fig.  h^.—Ophthnhrur  >liris},r,t  oj  Ihcji/lli.     (Ilirschrda.) 

1,  ganglion  of  Gasser;  2,  ophthalmic  division  of  the  fifth  ;  3,  lachrymal  branch  ;  A,  frontal 
branch ;  5,  external  frontal ;  6,  internal  frontal ;  7,  fiupra-trochlcar ;  8,  naaal 
branch;  ^^  external  nasal;  10,  internal  nasal;  11,  anterior  deep  temporal  nerve; 
12,  middle  deep  temporal  nerve;  13,  posterior  deep  temporal  nerve;  14,  origin  of 
the  superficial  temporal  nerve  ;  15,  great  superficial  petrous  nerve.  I  to  XII,  roots 
of  the  cranial  nerves. 


divides  into  three  large  nervous  trunks  called,  resi)ectively, 
the  ophthalmic,  the  superior  maxillary,  and  the  inferior  max- 
illary nerves,  which  escape  from  the  cavity  of  the  cranium 
through  different  foramina.*  The  motor  root  accompanies  the 
inferior  maxillary  nerve  until  it  has  escaped  from  the  cranium, 
when  it  unites  with  it. 


'  The  sphenoidal  fissure,  foramen  rotundum,  and  foramen  ovale  respectively  afford  a 
passage  for  these  branches  from  the  cranium. 


FUNCTION'S   OF  THE  FIFTH  NERVE. 


153 


TABLE   OF   THE   DISTRIBUTION^   OF   THE   FIFTH   CRAJs^IAL   KERVE.' 


fa.  OPHTHAL- 
MIC NERVE. 


r  (1)  Lachrymal  branch. 

(2)  Frontal  branch.  \  guP'a-oi'bital  nerve 
/  fcupra-trochlear  ner 


[^  (3)  Nasal  branch. 


h.  SUPERIOR 
MAXILLARY^ 


In  the  sj)hcno-maxil- 
lary  fossa. 


NERVE. 


In   the   infra-orbital  \ 


(  hjupra -trochlear  nerve. 

r  Ganglionic  nerve  (to  ciliary  ganglion). 
Long  ciliary  nerves. 
Inf  ra-troclilear  nerves. 
Internal  set.  To  septum  of  nose. 

(  To     mucous     mem- 
External  set.  -j      brane  and  integu- 

t  (      ment  of  nose. 

'  Orbital  or  Temporo-malar  nerve. 
Spheno-palatine  nerves  (to  Meckel's  gan- 
glion). 

Posterior    dental  (  ^"P^^^,^'^^    ^^^ntal 
nerve.  i      branches. 

(  Deep  dental  branches. 


c.  INFERIOR 
MAXILLARY 
NERVE. 


canal. 
On  the  face. 


From     the 
trunk. 


anterior 


From    the  posterior 
ti"unk. 


s  Anterior  dental  nerve. 

Palpebral  branches. 
Nasal  branches. 
Labial  branches. 

r  (1)  Masseteric  branch. 

I  (2)  Deep  temporal.  \  ^°*f"?^  ^Z'^^^^- 
I  (  Posterior  branch. 

(3)  l3uccAL  branch. 

(4)  Pterygoid.  \  Internal  branch. 
^  '  (  External  branch. 

(1)  Auriculo  -  tem- j  Auricular. 

PORAL  nerve.    (  Temporal. 

(2)  Gustatory  nerve. 

f  Mylo-hyoid. 
(8)  Inferior  dental]  Incisor. 
NERVE.  1  Mental, 

t  Dental. 


From  anatomical  points  which  have  been  mentioned,  and 
also  by  the  above  table,  the  fact  is  shown  that  the  ophthalmic 
and  the  superior  maxillary  nerves  possess  no  motor  power, 
while  the  inferior  maxillary  nerve  is  both  motor  and  sensory 
in  its  function.  It  has  been  mentioned  in  previous  pages, 
however,  that  a  vaso-motorial  influence  is  possessed  by  the 
ophthalmic  nerve,  and  also  a  direct  power  of  dilating  the 
jjupils  ;  but  these  effects  are  unquestionably  dependent  upon 
filaments  given  to  it  by  the  sympathetic  nerve. 

The  ultimate  distribution  of  the  three  branches  of  the  fifth 
nerve  may  possibly  be  made  more  clear  by  grouping  together 
the  efferent  and  afferent  fibers,  and  thus  separating  the  parts 


Copied  from  "Essentials  of  Anatomy"  (Darling  and  Ranney),  New  York,  1S80. 


154 


THE   CRANIAL  NERVES. 


Fig.  54. — A  diagram  of  the  dutribution  of  tlie  fifth  nerve} 

the  crus  cerebri  ;  2,  the  sensory  root  of  the  nerve ;  3,  the  motor  root  of  the  nerve  ;  4, 
the  Oasserian  ganglion^  upon  the  sensory  root  only ;  6,  the  ophthalmic  nerve,  passing 
through  the  sphenoidal  fissure ;  6,  the  superior  maxillary  nerve,  passing  through  the 
foramen  rotundum,  to  enter  the  spheno-maxillary  fossa ;  Y,  the  inferior  maxillarif 
nerve,  passing  through  the  fora^ncu  ovale  in  company  with  the  motor  root,  which 
soon  joins  it ;  8,  a  filament  sent  backward  from  the  ophthalmic  nerve  to  the  tento- 
rium cerebelli ;  %,  t\vQ  frontal  nerve ;  10,  the  lachrymal  nerve ;  11,  the  nasal  nerve; 
12,  the  supra-orbital  nerve,  passing  tii rough  the  foramen  of  the  same  name  ;  13,  the 
s^iipra-trorhlrar  nerve;  14:,  the  long  ciliary  nei'ves  to  the  iris;  15,  the  knticidar,  or 
ciliary  ganglion  ;  16,  the  temporo-malar  nerve,  showing  its  division  into  the  temporal 
branch  and  the  malar  branch;  17, the  spheno-palatine  nerves,  going  to  Meckel's  gan- 
glion ;  18,  the  posterior  dental  nerves,  given  off  just  before  the  superior  maxillary  nerve 
enters  the  infra-orbital  canal,  after  passing  throuajh  the  spheno-maxillary  fossa  ;  19, 
the  anterior  dental  nerves,  given  off  in  the  antrum  ;  20,  the  nemo-palatine  nerve,  es- 
caping at  the  anterior  palatine  foramen,  after  passing  through  the  antrum;  21,  the 
anterior  palatine  nerves,  after  escaping  from  the  posterior  palatine  foramen  ;  22,  the 
deep  tempyral  nerve;  23,  the  masseteric  branch  ;  24,  the  brjiceal  branch,  which  often 
also  supplies  the  external  pterygoid  muscle;  25,  the  pterygoid  branch,  going  chiefly 
to  the  internal  pterygoid  muscle ;  26,  the  posterior  palatine  nerves,  after  escaping 
from  the  posterior  palatine  foramen,  going  to  the  muscles  of  the  soft  palate ;  27,  the 
auriculo-temporal  nerve,  splitting  and  thus  embracing  the  middle  meningeal  artery  ; 
2S,  the  gustatory  or  lingua'  nerve,  distributed  to  the  anterior  two  thirds  of  the  tongue ; 
29,  the  inferior  dental  nerve,  passing  through  the  inferior  dental  canal,  beneath  the 
teeth  of  the  lower  jaw ;  30,  the  myl^-hi/oid  nerve,  a  branch  of  the  inferior  dental 
nerve;  31,  the  chorda  tympani  nerve,  joining  the  gustatory  nerve,  and  possibly  bring- 
ing to  it  the  perception  of  taste  ;  32,  the  middle  meningeal  artery  ;  ^Z,  the  fibers  going 
to  the  carotid  and  cavernous  plcxusics  of  the  sympathetic  system;  34,  the  Vidian 
nerve,  going  from  Meckel's  ganglion  to  the  Vidian  canal.  Ganglia  of  the  fifth  nerve. 
— L,  The  lenticular  ganglion,  sending  fibers  to  iris  and  ciliary  muscle ;  c,  the  Gafsc- 
rixn  ganglion  ;  o,  the  ofic  ganglion,  lying  on  the  inferior  maxillary  nerve  below  the 
foramen  ovale  ;  s,  the  submaxillary  ganglion,  connected  with  the  gustatory  and  chorda 
iympani  nerves ;    m,  Meckel's  ganglion,  lying  in  the  spheno-maxillary  fossa. 


^  Modified  fr:m  Flower. 


DISTRIBUTION^  OF  THE  FIFTH  NERVE 


155 


whicli  are  supplied  alone  with  sensation  from  those  to  which 
the  motor  root  is  eventually  distributed. 

The  efferent  fibers  of  the  fifth  pair  give  motor  power  to 
the  muscles  of  mastication,  viz.,  the  temporal,  masseter,  and 


v*,"'«^\l 


Fia.  55. — Infci'ior  maxillarif  division  of  the  ff(h .     (Ilirschfeld.) 

1,  branch  from  the  motor  root  to  the  masseter  muscle;  2,  filaments  from  this  branch  to 
the  temporal  muscle ;  3,  buccal  branch  ;  5,  6,  7,  branches  to  the  muscles ;  S,  aiiri- 
culo-temporal  nerve ;  9^  temporal  branches ;  \0,  auricular  branches;  l\,  anastomosis 
u'ith  the  facial  nerve  ;  12,  lingual  branch  ;  13,  branch  of  the  motor  root  to  the  mylo- 
hyoid muscle;  14,  15,  15,  inferior  dental  nerve,  loith  its  branches ;  16,  mental  branch; 
17,  anastomosis  of  this  branch  ivith  the  facial  nerve. 


pterygoids  ;  also  to  the  mylo-hyoid  and  anterior  belly  of  the 
■fcigastric,  and  to  the  tensor  palati  and  tensor  tympani.  They 
f  thus  control  not  only  the  physiological  act  of  mastication, 
but  also,  to  some  extent,  the  acts  of  deglutition  and  hearing. 
These  fibers  furthermore  afford  a  vaso-motor  influence  over 
various  vessels  in  certain  regions  of  the  head  and  face.  Secre- 
tory fibers  to  the  lachrymal  gland,  and,  according  to  some 


156 


THE  CRANIAL  NERVES. 


authors,  to  the  parotid  and  submaxillary  glands,  by  means  of 
fibers  derived  from  the  facial  nerve  (through  the  chorda  tym- 
pani  branch),  are  attributed  to  the  trigeminus.  By  these  fibers, 
the  secretions  necessary  to  the  perfect  performance  of  the 
parts  supplied  by  the  fifth  nerve  are  also  placed  under  its 
control,  thus  illustrating  again  that  beautiful  law  of  Nature 
in  arranging  the  nerves  in  accordance  with  harmony  of  action. 
Beside  the  efferent  fibers  possessed  by  the  fifth  nerve,  there 
exist  in  addition  certain  unnamed  fibers  which  control  the 
proper  nutrition  of  the  eye,  nose,  and  other  portions  of  the 
face.  These  latter  fibers  are  not  as  yet  fully  ascertained  so 
as  to  be  described  in  detail,  but  their  existence  seems  indi- 


FiG.  56. — Sujyerior  maxillary  division  of  the  fifth.     (Hirschfeld.) 

1,  ganc^lion  of  Gasser;  2,  lachrymal  branch  of  the  ophthalmic  division  ;  3,  superior  mar- 
illari/  division  of  the  fifth  ;  4,  orbital  brayich  ;  6,  lachrymo-palpehral  filament ;  6, 
malar  branch  ;  7,  temporal  branch  ;  8,  splleno-palatine  ganglion  ;  9,  Vidian  nerve ;  10, 
great  superficial  petrosal  nerve ;  11,  facial  nerve ;  1 2,  branch  of  the  Vidian  nerve ; 
13,  anterior  and  two  posterior  dental  branches  \  14,  branch  to  the  mucous  membrane  of 
the  alveolar  processes;  \1S^  terminal  branches  of  the  superior  maxillary  division  \  16, 
branch  of  the  facial. 


cated  by  the  fact  that,  after  section  of  the  fifth  nerve,  the 
cornea  becomes  cloudy ;  the  whole  eye  becomes  inflamed, 
only  to  subsequently  disorganize ;  the  mucous  membrane  of 
the  nose  is  similarly  destroyed,  and  ulcers  frequently  make 
their  appearance  upon  the  mucous  membrane  of  the  lips  and 
gums.     Snellen,  however,  considers  these  changes  as  the  ef- 


AFFERENT  FIBERS   OF  THE  FIFTH  NERVE.  157 

fects  of  the  mechanical  irritation  of  dirt,  which  the  mucous 
membranes,  no  longer  possessing  sensibility,  are  unable  to 
perceive. 

The  afferent  fibers  of  the  fifth  nerve  afford  general  sensa- 
tion to  the  entire  skin  of  the  head  and  face,  except  in  the 
occipital  region  and  the  back  and  lower  part  of  the  ear,' 


Fig.  57. — Superficial  branches  of  the  facial  and  thcffth.     (Kirschfeld.) 

1,  trunk  of  the  facial ;  2,  posterior  auricular  nerve  ;  3,  branch  which  it  receives  from  the 
cervical  plexus  ;  4,  occipital  branch  ;  5,  6,  branches  to  the  muscles  of  the  ear  ;  7,  digris- 
trie  branches  ;  8,  branch  to  the  stylo-hyoid  muscle  ;  9,  superior  terminal  branch  ;  10, 
temporal  branches  ;  11,  frontal  branches  ;  12,  branches  to  the  orbicularis  palpebrarum  ; 
13,  nasal,  or  suborbital  branches  ;  14,  buccal  branches  ;  15,  inferior  terminal  branch  ; 
16,  mental  branches  ;  17,  cervical  branches  ;  18,  superficial  temporal  nerve  (branch  of 
the  fifth);  19,  20,  frontal  nerves  (branches  of  the  fifth);  21,  22,  23,  24,  25,  26,  27, 
branches  of  the  fifth  ;   28,  29,  30,  31,  32,  branches  of  the  cervical  nerves. 

and  also  to  the  mucous  membranes  of  the  mouth,  with  the 
exception  of  the  posterior  pillar  of  the  fauces  and  the  poste- 

1  Hilton. 


158  THE  CRANIAL  yBRVBS. 

rior  third  of  the  tongue,  which  derive  their  sensation  by 
means  of  the  glosso -pharyngeal  nerves. 

The  accuracy  of  this  statement,  as  regards  the  distribution 
to  the  integument  of  the  ear,  which  is  now  accepted  by  most 
of  the  anatomical  authors  of  the  present  day,  was  strangely 
attested  to  by  facts  brought  under  the  notice  of  John  Hilton,' 
w^ho  was  thus  enabled  clinically  to  verify  the  exact  distribu- 
tion of  the  fifth  nerve  to  the  pinna  and  the  auditory  canal. 
It  seems  that  an  attempt  was  made  by  a  criminal  to  kill  his 
wife  by  cutting  her  throat,  but  that  the  attempt  was  not  suc- 
cessful, and  resulted  in  severing  the  auricular  branch  of  the 
second  cervical  nerve,  which  supplies  the  ear,  as  well  as  the 
fifth  cranial  nerve.  An  opportunity  was  thus  afforded  to  ex- 
amine, by  the  use  of  nsedle  points,  the  state  of  sensibility  of 
the  different  portions  of  the  ear,  and  to  decide,  by  the  loss 
of  sensibility,  the  exact  regions  which  the  second  cervical 
nerve  supplied.  It  was  thus  proven  that  the  uppe?'  and  ante- 
rior part  of  the  ear,  and  also  the  auditory  canal,  was  sup- 
plied by  the  fifth  cranial  nerve ;  and  that,  therefore,  these 
parts  are  in  direct  nervous  communication  with  the  forehead, 
temple,  face,  nose,  teeth,  and  the  tongue. 

It  can  thus  be  easily  understood  why  pain  in  the  auricular 
region,  as  evidenced  in  cases  recited  later  on,  may  prove  a 
most  valuable  diagnostic  sign  of  irritation  of  some  of  the  other 
branches  of  the  fifth  nerve,  distributed  to  the  regions  which 
are  associated  by  means  of  this  nerve  with  the  ear,  although 
apparently  having  no  anatomical  relation  with  it. 

In  the  partly  diagrammatic  representation  of  the  distri- 
bution of  the  nerves  to  the  cutaneous  surface  of  the  head,  the 
outlines  of  the  various  regions,  represented  as  supplied  by 
the  different  nerves,  are  as  nearly  accurate  as  careful  investi- 
gation can  determine  them."  It  will  be  perceived  that  nine, 
out  of  the  fourteen  regions  mapped  out  upon  the  head  and 
neck,  are  supplied  with  sensation  by  some  of  the  branches  of 

>  "  Rest  and  Pain,"  London  (New  York,  18 TO). 

*  As  the  boundaries  of  the  regions  supplied  by  any  nerve  gradually  shade  off  into 
neighboring  regions,  it  is  not  well  to  rely  upon  the  cxircme  area  of  any  region  in  testing 
the  special  sensibility  of  any  nerve. 


CUTANEOUS  BLANCHES  OF  THE  FIFTE  NERVE,        159 

the  fifth  cranial  nerve,  while  the  remaining  five  are  supplied 
by  branches  of  the  cervical  plexus,  with  the  exception  of  that 
region  to  which  the  great  occipital  nerve  is  distributed. 

It  can  easily  be  understood,  from  what  has  already  been 


Fig.  58  — The  nervous  distribution  of  the  head.     (After  Flower,  but  slightly  modified.) 

1,  region  supplied  by  the  supra-orbital  branch  of  the  fifth  nerve;  2,  region  supplied  by 
the  mpra-lrochUar  branch  of  the  filth  nerve  ;  3,  region  supplied  by  the  infra-troch- 
lear  branch  of  the  fifth  nerve  ;  4,  region  supplied  by  the  infra-orbital  branch  of  the 
fifth  nerve ;  5,  region  supplied  by  the  buccal  branch  of  the  fifth  nerve  ;  6,  region  sup- 
plied by  the  mental  branch  of  the  fifth  nerve  ;  7,  region  supplied  by  the  superficial 
cervical  from  the  cervical  plexus  ;  8,  region  supplied  by  the  great  auricular  from  the 
cervical  plexus ;  9,  region  supplied  by  the  iemporo-malar  bianch  of  the  fifth  nerve ; 
10,  region  supplied  by  the  lachrymal  branch  of  the  fifth  nerve  ;  11,  region  supplied 
by  the  auriculo-tcmporal htdincXi  of  the  fifth  nerve;  12,  region  supplied  by  the  great 
occipital  (a  spinal  nerve) ;  13,  region  supplied  by  the  small  occipital  from  the  cervical 
plexus ;  14,  region  supplied  by  the  supi-a-dlavicular  from  the  cervical  plexus. 

said  as  to  the  manner  of  employing  the  nerves  as  guides  to 
diagnosis,  that  a  careful  study  of  the  limits  of  each  of  these 
regions  of  the  head  may  often  enable  the  physician  to  explain 
symptoms  which  might  otherwise  seem  obscure ;  and  also 
enable  him  to  use  the  symptom  of  local  pain,  whenever  pres- 
ent, as  a  signal  which  Nature  often  gives  of  disease  in  parts 
possibly  far  removed  from  the  seat  of  pain,  but  still  inti- 
mately connected  to  it  by  means  of  its  nervous  supply. 

EFFECTS   OF   SECTIOX   OF  THE   FIFTH    :N^EEVE. 

Many  points  of  practical  value  dependent  upon  the  fifth 
nerve  can  be  better  understood  when  the  effects  of  its  divis- 
ion have  been  considered  in  detail.  If  the  fifth  nerve  be 
divided,   sensation  is  immediately  destroyed   in    all  those 


160  THE  CRANIAL  NERVES. 

portions  of  the  head  and  face  to  which  the  efferent  nerves 
are  distributed  ;  the  power  of  mastication  is  lost ;  the  secre- 
tions of  the  lachrymal,  parotid,  and  submaxillary  glands  are 
rendered  deficient ;  the  act  of  deglutition  becomes  imper- 
fect, since  some  of  the  muscles  required  for  its  performance 
are  paralyzed,  and  since  the  tongue  is  unable  to  perceive  the 
bolus  of  food,  and  therefore  can  not  x>roperly  direct  its 
movements ;  and,  finally,  Jiearing  is,  to  a  certain  extent, 
impaired,  since  the  tensor  tympani  muscle '  has  lost  its  motor 
power. 

In  addition  to  these  direct  effects  of  section,  secondary 
results  are  manifested  in  those  forms  of  ulceration  which 
have  been  previously  referred  to,  and,  eventually,  in  the  de- 
struction of  sight  and  smell. 

It  may  be  noticed  that  the  effect  of  section  of  the  fifth 
nerve  upon  the  special  sense  of  taste  has  not  been  mentioned. 
It  was  formerly  supposed  that  the  gustatory  fibers  of  the  fifth 
nerve  afforded  the  sense  of  taste  to  the  anterior  two  thirds  of 
the  tongue  ;  but  it  is  now  urged  by  many  that  the  fifth  nerve 
is  simply  a  nerve  of  sensation  to  that  organ,  and  that  its  fibers 
are  employed  exclusively  in  the  appreciation  of  the  sensations 
of  touch  and  feeling,  while  the  true  gustatory  fibers  of  that 
portion  of  the  tongue  are  derived  from  the  chorda  tympani 
branch  of  the  facial  nerve.  In  support  of  this  view,  cases  have 
been  observed  where  the  chorda  tympani  has  been  affected, 
either  by  disease  or  in  consequence  of  injury  within  the 
middle  ear,  and  the  sense  of  taste  has  been  impaired  ;  but,  on 
the  other  hand,  cases  have  been  also  recorded  where  the  fifth 
nerve  was  alone  diseased,  and  yet  taste  was  destroyed  in  thf^ 
anterior  two  thirds  of  the  tongue.  It  is  such  cases  as  tli< 
latter  that  still  lead  some  physiologists  to  believe  that  the 
chorda  tympani  nerv^e  only  controls  t\\eflow  of  the  saliva^  and 
that  impairment  of  this  secretion  impairs  or  destroys  the  spe- 
cial sense  of  taste  afforded  by  the  gustatory  branch  of  the 
fifth  nerve. 

'  According  to  Lticac's  recent  experiments  ("  Berlin,  kiln.  Wschr.,"  1874),  the  tensor 
tympani  muscle  presides  over  the  accommodation  for  musical  tones. 


NEURALGIA    OF  THE  FIFTH  NERVE.  lei 

CLIXICAL   POINTS   AFFOKDED   BY   THE   FIFTH   NERVE. 

The  fifth  nerve  may  be  the  seat  of  neuralgia,  spasm,  or 
paralysis.  The  type  of  neuralgia  (called  tic-douloureux,  the 
facial  pain  of  Fothergill,  and  "  prosopalgia  ")  dependent  upon 
the  fifth  nerve  affects  only  the  sensory  trunks  ;  the  spasms 
may  be  of  a  tonic  or  clonic  type,  and  are,  of  course,  confined 
to  the  muscles  supplied  by  the  motor  branches  of  the  nerve  ; 
while  the  paralytic  condition  can  affect  the  sensory  trunks, 
producing  anaesthesia  of  the  parts  to  which  the  affected  nerve 
is  distributed,  or  the  motor  filaments  may  be  impaired,  thus 
destroying  the  power  of  normal  movement  in  the  muscles  of 
mastication  and  the  mylo-hyoid.  So  many  points  of  clinical 
interest  and  practical  value  pertain  to  these  various  condi- 
tions that  each  will  be  considered  somewhat  in  detail. 

NEURALGIA   OF  THE  TRIGEMINUS   NERVE. 

The  various  forms  of  tic-douloureux  are  so  Commonly  met 
with,  and  prove  so  obstinate  to  treatment,  as  well  as  distress- 
ing to  the  patient,  that  a  practical  knowledge  of  the  disease 
can  not  be  gained  without  a  careful  study  of  the  various 
causes  which  have  been  found  to  produce  it. 

Among  the  reported  cases  of  this  affection,  there  have 
been  discovered,  as  exciting  causes,  the  following  conditions  : 
Tumors  of  the  middle  fossa  of  the  skull  or  of  the  base  of 
the  brain,  producing  neuralgia  so  long  as  irritation  only  is 
produced,  but  anaesthesia  when  degeneration  of  the  nerve 
trunks  begins  ;  accumulations  of  pus  within  the  cranial  cav- 
ity ;  tumors  of  the  pons  Varolii  ;  morbid  processes  in  the 
regions  adjacent  to  the  ganglion  of  Gasser  ;  and  aneurism  of 
the  internal  carotid  artery  '  within  the  sella  turcica.  Diseases 
of  the  cervical  portion  of  the  spinal  cord,  if  high  up,  may  cre- 
ate neuralgia  of  the  fifth  pair,  by  irritating  the  fibers  of  that 
nerve  which  arise  from  the  lower  part  of  the  medulla.  Peri- 
ostitis of  the  bony  orifices,  through  which  the  various  branches 
of  the  fifth  nerve  pass,  may  create  such  pressure  as  to  produce 

'  Romberg's  case. 


162  THE  CRANIAL  NERVES. 

the  most  severe  and  persistent  neuralgias  ;  for  this  reason  the 
supra-orbital,  infra-orbital,  zygomatic,  superior  and  inferior 
dental  branches  are  more  liable  to  be  the  seat  of  pain  than 
the  branches  which  pass  through  such  large  openings  as  the 
sphenoidal  and  spheno-maxillary  fissures.'  Exostoses  of  the 
bones,  especially  of  the  upper  and  lower  jaws,  may  create  the 
most  severe  type  of  neuralgia  by  pressure  upon  the  neighbor- 
ing nerve  trunks.  Exposure  to  cold  or  dampness  will  pro- 
duce it,  being  one  of  the  most  frequent  of  the  trivial  causes. 
Finally,  inflammatory  changes  in  the  ganglia "  attached  to  the 
nerve,  the  enlargements  and  nodosities  found  upon  resected 
nerves,  an  exostosis  of  a  wisdom  tooth,"  caries  and  osteo- 
phytes of  the  bony  canals  through  which  branches  of  the 
nerve  pass,  and  neuroma  of  the  ganglion  of  Gasser  protrud- 
ing through  the  foramen  ovale,*  have  been  known  to  produce 
the  most  severe  neuralgia. 

The  symptoms  of  tic- douloureux  are  of  the  most  distressing 
character.  The  pain  is  usually  extremely  violent,  and  the 
patients  will  describe  it  to  you  as  of  a  burning,  piercing,  or 
shooting  character.  It  is  liable  to  be,  at  first,  paroxysmal ; 
but,  if  due  to  organic  disease,  it  may  gradually  become  more 
or  less  constant.  The  continuous  pain  is,  however,  usually 
limited  to  certain  well-defined  spots  of  extreme  sensitiveness 
to  pressure,  which  the  patient  can  readily  point  out  to  you 
(the  "puncta  dolorosa  "  of  Yalleix).  Thus,  the  first  branch  of 
the  trigeminus  (the  ophthalmic)  presents  six  such  points,  each 
indicating  some  one  of  its  subdivisions.  These  are  situated, 
respectively,  over  the  supra-orbital  foramen  ;  in  the  center  of 
the  upper  eyelid  ;  a  frontal  point  over  the  escape  of  the  nerve 
of  the  same  name  ;  one  at  the  outer  angle  of  the  eye,  for  the 
lachrymal  branch ;  and  two  at  the  inner  angle  of  the  eye, 
upon  the  nose,  representing  the  inferior  trochlear  and  the 
ethmoidal  nerves. 

In  the  region  supplied  by  the  superior  maxillary  nerve 
and  its  branches,  there  may  exist  a  malar  point,  an  infra- 

^  Ilyrtl,  as  quoted  by  Rosenthal.  '  Cases  of  Carnochan  and  Wcdl. 

*  Thompson,  as  quoted  by  Rosenthal.  ^  Chouppe's  case. 


NEURALGIA   OF  THE  FIFTH  KERVE.  163 

orbital  point,  a  point  in  the  palate,  and  one  on  the  gum  of  the 
upper  jaw. 

In  the  region  of  the  inferior  maxillary  nerve,  the  points  of 
tenderness  are  situated  in  front  of  the  tragus  of  the  ear  (the 
temporal  point) ;  one  in  the  parietal  region,  where  the  frontal, 
occipital,  and  temporal  nerves  meet ;  one  over  the  temporo- 
maxillary  joint ;  a  point  upon  the  tongue  for  the  lingual 
branch ;  and  one  upon  the  integument  of  the  chin,  for  the 
mental  nerve. 

Painful  points  are  often  detected  by  pressure  in  the  region 
of  the  spinous  and  transverse  processes  of  the  cervical  verte- 
brae (the  ''point  apophysaire"  of  Trousseau). 

These  puncta  dolorosa  are  usually  the  starting  points  for 
the  pain  of  the  acute  paroxysms,  from  which  the  pain  radiates 
along  the  course  of  the  nerves  of  the  region  affected.  In  some 
cases,  these  x^oints  of  tenderness  may,  however,  be  absent,  when 
a  central  origin  of  the  disease  may  reasonably  be  suspected. 

The  relation  of  the  filaments  of  the  fifth  nerve  with  certain 
vaso-motor  fibers  causes  this  type  of  disease  to  be  often  asso- 
ciated with  certain  disorders  of  secretion,  since  the  vessels  of 
the  glands  of  the  affected  region  are  liable  to  dilate  after  an 
acute  paroxysm  cf  pain.  We  can  thus  explain  the  abundant 
How  of  tears  after  an  attack  of  neuralgia  of  the  ophthalmic 
branch  ;  and  of  nasal  mucus  and  saliva,  when  the  second  and 
third  branches  of  the  trigeminus  are  involved.  Profuse  sweat- 
ing of  the  region  of  the  face  affected  is  also  sometimes  weU 
marked  both  during  and  after  the  paroxysm. 

The  vaso-motor  communication  may  also  explain  why  we 
have  reported  cases  of  local  swelling,  redness,  elevation  of  the 
temperature,  and,  sometimes,  erysipelatous  inflammation  of 
the  affected  region  ;  and  why  the  hair  has  been  observed  to 
fall  out,  and  the  skin  to  become  discolored  and  roughened. 
Hypertrophy  of  the  cheek  has  been  noticed,  as  a  result  of  tic- 
douloureux,  by  Niemeyer,  Brodie,  Romberg,  and  Notta  ;  and 
ophthalmia  has  been  produced  by  a  similar  condition  confined 
to  the  first  branch  of  the  fifth  ner\^e.  When  the  nerve  trunks, 
which  at  first  were  the  seat  of  neuralgia,  become  destroyed  or 


164  THE  CRANIAL  NERVES. 

seriously  impaired  by  pressure  or  granular  degeneration,  the 
face  may  undergo  atrophy. 

Neuralgias  of  the  fifth  nerve,  when  due  to  cerebral  tumors^ 
are  often  complicated  by  other  symptoms  which  greatly  assist 
in  the  diagnosis  ;  among  the  more  prominent  of  which  may  be 
mentioned  diplopia,  vertigo,  chronic  cephalalgia,  spasms  of 
certain  groups  of  muscles,  paralysis  of  various  types,  and  the 
absence  of  the  puncta  dolorosa,  whose  situations  have  already 
been  mentioned. 

Tic-douloureux  is  not  to  be  confounded  with  pain  depend- 
ent upon  the  decay  of  teeth,  inflammation  of  the  temporo- 
maxillary  articulation,  tumors  of  the  antrum,  or  extension  of 
inflammation  to  that  cavity  from  an  acute  attack  of  coryza, 
migraine,  or  the  facial  pains  of  lead  poisoning,  hysteria,  or 
spinal  affections.  It  is  more  common  in  women  than  in  men  : 
and  most  frequent  between  the  ages  of  thirty  and  fifty.  It  i- 
more  liable  to  occur  in  cold  months  than  when  the  weather  i 
warm  (provided  it  be  not  due  to  actual  disease) ;  and  it  may 
follow  traumatism,  senile  changes  in  the  blood-vessels,  and 
malarial  poisoning. 

SPASM   DUE  TO  THE  TRIGEMINUS   N^ERVE. 

The  jaw  may  be  rendered  immovable,  as  in  tetanus,  by  the 
masseter,  temporal,  and  pterygoid  muscles,  all  of  which  are 
supplied  with  motor  power  by  the  fifth  nerve.  The  same  form 
of  spasm  may  be  occasionally  observed  in  attacks  of  hysteria. 

Clonic  spasm  of  the  temporal  and  masseter  muscles,  alter- 
nating with  that  of  the  depressors  of  the  jaw  (the  mylo-hyoid 
and  the  anterior  belly  of  the  digastric),  produces  the  chatter- 
ing of  the  teeth  so  often  seen  in  the  chill  of  inflammatory  dis- 
eases and  fevers  and  after  exposure  to  cold. 

The  pterygoid  muscles,  by  a  tonic  contraction,  may  pro- 
duce the  (grinding  of  the  teeth ;  a  displacement  of  the  jaw 
to  one  side,  during  an  hysterical  paroxysm,  which  lasted  some 
days,  is  reported  by  Leube.* 

■*  As  quoted  by  Rosenthal :  "  A  Clinical  Treatise  of  the  Diseases  of  the  Nervous  Sys- 
tem" (Putzel's  translation,  New  York,  1879). 


SPASM  A^D  PARALYSIS  OF  THE  FIFTH  NERVE.       165 

Spasms  of  the  muscles  supplied  by  the  trigeminus  may  be 
jj  the  result  of  apoplexy,  cerebral  softening,  meningeal  exuda- 
fi  tion,  lesions  of  the  pons  Varolii  and  medulla  oblongata,  hys- 
,    teria,  epilepsy,  tetanus  hysteria,  hydrophobia,  tumors  irritat- 

Sinor  the  ganglion  of  Gasser,  peripheral  irritation,  reflex  causes 
dental  pain,  ulceration  of  the  tongue  or  mouth,  intestinal 
,  ^.  uterine  irritation,  teething,  etc.),  and  rheumatism. 
1  In  rare  cases,  the  depressors  of  the  jaw  may  be  the  seat  of 
!  localized  spasm,  in  which  event  the  mouth  may  be  kept  wide 
r    open  for  a  longer  or  shorter  period. 

r! 

I  PARALYSIS   OF   THE   TRIGEMIKUS   NEEVE. 

i        ^  . 

I  It  IS  a  rare  occurrence  to  observe  a  simultaneous  paralysis 

of  the  motor  and  sensory  roots  of  the  trigeminus  ;  although 

[i  anaesthesia  of  parts  supplied  by  the  branches  derived  from 
the  sensory  root  may  occur  from  central  causes,  and  is  per- 
haps more  frequent  than  those  symptoms  dependent  upon 
lesions  involving  the  motor  root.  In  lesions  confined  to  the 
cerebral  ganglia  or  cortex,  however,  the  motor  root  is  more 
often  impaired  than  the  sensory  portion,  while  the  sensory 
root,  or  some  of  its  branches,  is  frequently  affected  from 
causes  outside  of  the  cranial  cavity. 

In  studying  the  condition  of  trigeminal  anaesthesia,  it  must 
be  prefaced  that  the  regions  affected,  and  therefore  the  results 
of  the  impaired  nervous  function,  differ  with  the  exciting 
cause,  since  a  central  lesion  is  liable  to  involve  all  of  the  sen- 
sory branches  of  the  nerve ;  while  an  external  cause  usually 
affects  some  individual  branch. 

The  central  lesions  of  this  disease  comprise  apoplectic 
clots ;  destructive  lesions  producing  ataxia ;  hysteria ;  local 
diseases  or  exudations  which  involve  the  large  root  of  the  fifth 
nerve  between  the  pons  Varolii  and  the  ganglion  of  Gasser ; 
and  lesions  of  the  medulla  oblongata,  thus  affecting  its  fibers 
of  origin. 

The  external  causes  include  all  forms  of  traumatism ; 
exposure  to  cold  or  heat ;  surgical  procedures  ;  caries  or  peri- 
ostitis of  the  bony  canals  ;  suppuration  of  the  soft  tissues  ad- 

13 


166  THE  CRANIAL  NERVES. 

joining  the  affected  nerve ;  local  tumors  and  inflammatory 
exudations ;  and  certain  blood  conditions  accompanied  by 
nerve  sclerosis  (chiefly  Norwegian  leprosy).' 

The  condition  of  facial  anaesthesia  may  be  complete,  when 
sensibility  to  contact,  pain,  heat,  or  cold  is  abolished ;  or  par- 
tial, when  extreme  impressions  can  be  perceived,  and  often 
differentiated  as  to  the  peculiar  character  of  each.  The  needle 
points,  the  compass,  and  the  electric  brush  are  all  employed 
in  the  examination  of  such  a  patient,  in  order  to  decide 
as  to  the  extent,  character,  and  degree  of  the  existing  pa- 
ralysis. 

If  the  opJithalmic  nerve  be  the  seat  of  anaesthesia,  we  may 
observe  a  contracted  state  of  the  pupil,''  insensibility  of  the 
mucous  lining  and  integument  of  the  upper  eyelid,  insensi- 
bility of  the  skin  of  the  forehead  and  the  external  and  in- 
ferior parts  of  the  nose,  and  a  total  absence  of  the  sense  of 
contact  in  the  anterior  portions  of  the  mucous  membrane  of 
the  nostril. 

K  the  superior  maxillary  nerve  alone  be  affected,  the  skin 
and  mucous  lining  of  the  lower  eyelid,  the  integument  of  the 
cheek,  lower  half  of  the  nose,  and  the  corresponding  half  of 
the  upper  lip,  show  an  entire  or  partial  abolition  of  sensibility ; 
while  the  mucous  membranes  of  the  middle  and  posterior  por- 
tions of  the  nasal  cavity,  of  the  roof  of  the  palate,  and  the  en- 
tire soft  palate  and  uvula,  are  similarly  affected.  The  teeth 
and  gums  of  the  upper  jaw  will  also  be  in  the  anaesthetic  con- 
dition. 

If  the  inferior  maxillary  nerve  be  the  seat  of  disease,  with- 
out impairment  of  the  motor  root  of  the  nerve,  the  integument 
of  the  outer  surface  of  the  ear,  above  the  auditory  canal,'  of 
the  temporal  region,  of  the  corresponding  half  of  the  lower 
lip,  and  in  front  of  the  temporo-maxillary  articulation,  will  be 
destitute  of  sensibility.  The  mucous  membrane  of  the  corre- 
sponding side  of  the  lower  lip,  tongue,  cheek,  tonsil,  and  gum 
of  the  lower  jaw  will  be  also  anaesthetic,  while  the  teeth  of  the 

'  See  investif^ations  of  Daniellsen  and  Boeck,  as  quoted  by  Rosenthal, 

'  For  effects  of  nerve  influences  on  the  pupil,  see  page  1 33  of  this  volume. 

'  For  researches  of  Hilton  on  this  point,  sec  page  158  of  this  volume. 


TROPHIC  EFFECTS  OF  TRIGEMINAL  PARALYSIS.       167 

corresponding  side  of  tlie  lower  jaw  will  likewise  be  deprived 
of  sensibility. 

If  you  will  recall  the  points  which  were  made  in  reference 
to  the  effects  of  section  of  the  trigeminus,  you  will  be  better 
able  to  understand  why  paralysis  of  any  portion  of  this  nerve 
should  be  followed  by  symptoms  of  late  development,  due, 
apparently,  to  some  alteration  in  the  nutrition  and  reactive 
power  of  the  regions  supplied  by  the  nerve  which  is  diseased. 
Tou  will  remember  that  the  existence  of  certain  unnamed 
fibers,  called  ''trophic  fibers,"  was  mentioned,  whose  close 
connection  with  the  sympathetic  nerve  is  highly  probable, 
and  whose  function  seems  to  be  to  control  and  regulate  the 
blood  supply  of  the  regions  to  which  they  pass.  Now,  it  is 
clinically  observed  that  the  paralysis  of  any  of  the  three 
large  branches  of  the  trigeminus  is  followed  by  certain  ulcer- 
ative and  suppurative  processes  in  the  regions  rendered  anes- 
thetic, and  that  these  effects  are  the  most  prominent  and 
serious  when  the  ophthalmic  nerve  is  affected. 

Landmann  and  Bell  were  the  first  observers  to  point  out 
that,  in  the  human  subject,  purulent  destruction  of  the  eye 
was  liable  to  follow  pressure  upon  the  trigeminus  from  tumors 
in  the  region  of  the  ganglion  of  Gasser ;  while  Magendie 
(1824),  Bock  (1844),  Snellen  (1858),  Spencer  Watson  (1874), 
Samuel  (1860),  and  Meissner  have  done  much  to  bring  the 
results  of  defective  nutrition,  following  impairment  of  nerve 
supply,  to  professional  notice.  It  might  add  much  to  the 
interest  of  this  volume  to  enter  into  the  details  of  the  inter- 
esting experiments  and  clinical  observation,  which  have  now 
become  quite  extensive  regarding  this  subject,  but  it  will  ex- 
ceed the  scope  of  this  course  to  more  than  hastily  sketch  the 
results  obtained.  The  opinion  of  Snellen,  that  the  ulceration 
of  the  cornea  and  the  suppurative  conjunctivitis  which  fol- 
lows anaesthesia  of  the  ophthalmic  nerve  were  the  mechanical 
effects  of  the  irritation  of  dirt  which  the  conjunctiva  was  no 
longer  capable  of  perceiving,  seems  to  have  been  confirmed  by 
Watson '  and  Baerwinkel,"  who  found  that  an  artificial  cleans- 

'  "Med.  Times,"  1874.  ^  "Arch.  f.  klin.  Med.,"  18Y4. 


1G8  THE  CRAXIAL  NERVES. 

ing  and  closure  of  the  eyelids  caused  recovery,  without  any 
effect  upon  the  nerve  condition.  It  was  apparently  also  proven 
by  Bock  and  Samuel  that  the  condition  of  ansesthesia  was  not 
necessary  to  the  development  of  these  later  processes,  resulting 
in  destruction  of  tissue,  since  the  same  results  were  observed 
when  hypersesthesia  existed.  In  reference  to  the  course  of 
the  ''trophic  fibers"  of  the  ophthalmic  nerve,  the  researches 
of  Meissner  and  Schiif '  seem  to  locate  their  situation  in  the 
central  portion  of  the  nerve,  since  the  other  parts  seem  to 
preside  over  sensation  only.  Finally,  the  interesting  experi- 
ments of  Sinitzin,"  made  in  1871,  show  some  remarkable 
effects  of  the  removal  of  the  superior  cervical  ganglion  of  the 
sympathetic  nerve  upon  trigeminal  ophthalmia  ;  since  it  was 
often  cured  when  once  started,  and  prevented  in  every  case 
where  it  was  done  before  the  trigeminus  was  divided. 

We  know,  irrespective  of  the  theories  of  its  causation, 
that  the  destruction  of  the  sensory  root  of  the  fifth  nerve  is 
liable  to  be  followed  by  destruction  of  sight,  interference 
with  the  sense  of  smell,  ulceration  of  the  nose  and  gums,  a 
tendency  to  inflammation  and  abscess  of  the  soft  tissues,  and, 
possibly,  to  gangrene. 

It  is  of  practical  importance,  however,  to  discriminate 
between  that  form  of  trigeminal  anaesthesia  dependent  upon 
central  lesions  and  that  due  to  external  pressure  or  disease. 

We  may  remember  that  the  central  form  is  usually  con- 
fined to  the  inferior  maxillary  portion  of  the  nerve ;  that  a 
previous  history  of  cerebral  disease  wHl  often  be  found  ;  that 
paresis  or  paralysis  of  the  muscles  of  the  face,  tongue,  jaws, 
or  limbs  will  possibly  coexist ;  and  that,  if  the  lesion  be  a 
tumor  at  the  base  of  the  cerebrum,  cephalalgia,  neuralgias  of 
special  branches  of  the  trigeminus,  and  a  simultaneous  affec- 
tion of  some  of  the  adjacent  nerves  of  the  cranium  may  be 
discovered. 

If  the  cause  is  outside  of  the  cranium  (provided  it  be  not 
due  to  syphilis,  rheumatic  diathesis  or  traumatism),  we  may 
expect  to  find  evidences  of  the  previous  existence  of  abscess, 

1  " Centralbl.,"  1807.  «  "Med.  Centralbl.,"  1871. 


DIAGNOSTIC  VALUE  OF  THE  FIFTH  NERVE.  169 

periostitis  of  some  of  the  osseous  canals  through  which  the 
various  branches  of  the  trigeminus  pass,  or  of  local  tumors 
which  are  creating  pressure  upon  some  nerve  trunk  or  its 
terminal  filaments. 

The  motor  root  of  the  fifth  nerve  may  he  impaired  from 
the  pressure  exerted  by  meningeal  exudation,  extravasations 
of  blood,  or  tumors  Avithin  the  cranium  ;  while  it  is  frequently 
involved  (after  the  sensory  portion  of  the  trigeminus)  during 
the  development  of  some  type  of  basilar  affection.  The  re- 
sults are  manifested  by  a  paralysis  of  the  muscles  of  mastica- 
tion upon  the  side  where  the  nerve  is  diseased,  except  the 
buccinator  muscle,  which  derives  its  motor  power  from  the 
facial  nerve.  The  healthy  muscles  of  the  opposite  side  tend 
to  crowd  the  lower  jaw  toward  the  affected  side  of  the  face 
during  mastication,  giving  a  peculiar  expression  during  the 
act  of  eating. 

DIAGNOSTIC   VALUE   OF  THE   FIFTH   KERVE. 

To  what  extent  the  distribution  of  the  fifth  nerve  is  of 
practical  value  in  diagnosis  may  be  estimated  by  the  perusal 
of  the  lectures '  of  Sir  John  Hilton  upon  the  significance  of 
pain  and  the  use  of  rest  as  its  cure.  Cases  have  been  reported 
by  Paget,  in  his  lectures  on  surgical  pathology,  and  also  by 
Anstie,'*  where  the  hair  of  the  entire  scalp  has  turned  white 
after  a  severe  attack  of  neuralgic  headache ;  and  another  is 
reported  by  Anstie,  where  the  hair  of  the  eyebrow  alone  be- 
came perfectly  blanched  from  pain  in  that  region  dependent 
upon  the  supra-orbital  nerve.  Hilton  reports  a  case  where  the 
hair  of  the  temple^  from  the  irritation  excited  in  the  dental 
branches  of  the  fifth  nerve  through  a  decayed  molar  tooth, 
became  suddenly  gray  (the  temple  being  the  region  supplied 
by  the  auriculo-temporal  branch  of  the  same  nerve) ;  and  an- 
other where  an  obstinate  form  of  ulcer  in  the  auditory  canal, 
which  was  very  painful,  and  had  withstood  all  methods  of 
treatment,  was  cured  by  the  extraction  of  a  decayed  tooth  in 
the  upper  jaw ;  again  illustrating  the  fact  that  irritation  of 

^  "  Rest  and  Pain,"  London  (Xew  York,  IS^Q).  '^  "  Lancet,"  1866, 


170  THE  CRANIAL  NERVES. 

one  branch  (the  dental)  can  create  disease  at  the  seat  of  distri- 
bution of  another  branch  of  the  same  nerve  (the  auriculo- 
temporal). 

The  temjporo-maxillary  articulation  has  often  been  known 
to  assume  a  condition  of  immobility  during  an  attack  of  ear- 
ache, and  to  be  immediately  relieved  by  the  application  of  an 
anodyne  to  the  terminal  filaments  of  the  fifth  nerve  in  the 
canal ;  thus  illustrating  the  effect  of  irritation  of  one  branch 
(the  auriculo-temporal)  upon  the  others  which  supply  the 
muscles  of  mastication,  causing  them  to  contract  and  thus  fix 
the  joint. 

Again,  a  furred  condition  of  the  lateral  lialf  of  the  tongue 
may  almost  be  considered  a  pathognomonic  sign  of  some 
source  of  irritation  to  the  fifth  nerve,  which  thus  manifests 
itself  in  the  peripheral  distribution  of  one  of  its  branches  (the 
gustatory  nerve).* 

Chronic  ulceration  of  the  cornea  has  also  been  reported  by 
Anstie  as  a  symptom  produced  by  some  source  of  irritation  of 
the  fifth  nerve,  far  removed  from  the  seat  of  disease. 

The  intimate  communication  of  the  internal  portions  of  the 
mouth  with  the  eye,  ear,  and  nose  often  accounts  for  many 
curious  symptoms,  which  it  would  be  difficult  to  account  for, 
did  we  not  know  that  pain  may  be  felt  at  any  branch  of  a 
nerve,  when  one  of  its  trunks  is  irritated.  I  have,  at  the 
present  time,  a  patient  under  my  care,  who  is  suffering  from 
an  obstinate  ulceration  of  the  tongue,  and  who  had,  previous 
to  his  consulting  me,  been  treated  for  an  inflammatory  condi- 
tion of  the  ear,  on  account  of  a  constant  and  severe  pain, 
which  was  considered  as  separate  and  distinct  from  the  trou- 
ble which  was,  at  the  same  time,  affecting  his  tongue.  A  sim- 
ple gargle  of  opium,  which  I  ordered  him  to  hold  for  fifteen 
minutes  in  his  mouth  at  intervals,  relieved  the  symptom  in  a 
very  short  time. 

A  case  is  reported  by  Hilton  where  an  enlarged  cervical 
gland  appeared  with  a  simultaneous  discharge  from  the  au- 
ditory canal^  and  where  the  explanation,  by  which  a  decayed 

'  Bransby  Cooper  ;  John  Hilton. 


DIAGNOSTIC  VALUE   OF  THE  FIFTH  NERVE.  lYi 

tooth  was  diagnosed  as  the  cause  of  the  condition,  was  as 
follows :  The  irritated  dental  branches  of  the  fifth  nerve 
caused  an  inflammation  of  the  auditory  canal,  which  is  sup- 
plied by  another  branch  (the  auricular  of  the  auriculo-tem- 
poral)  ;  this  inflammation  was  followed  by  suppuration 
and  excoriation  of  that  canal,  and,  subsequently,  by  ab- 
sorption of  the  discharges  by  the  lymphatic  vessels,  thus 
producing  the  enlarged  gland  of  the  neck.  This  expla- 
nation may  seem  a  roundabout  way  of  reaching  a  diagnosis, 
but  the  result  of  drawing  the  tooth  proved,  in  this  case, 
how  well  anatomy  may  guide  us,  if  we  only  follow  its  teach- 
ings. 

Earache  may  not  always  be  due  to  the  fifth  nerve,  even 
when  it  is  confined  to  the  external  portion  of  the  organ, 
since  the  second  cervical  nerve  supplies  the  lower  and  hacTc 
part  of  the  external  ear,  so  that  pain  in  that  region  should 
lead  us  also  to  look  for  some  cause  of  irritation  to  that  nerve. 

The  distribution  of  nerves  to  the  scalp,  as  shown  in  the 
figure  on  page  159,  renders  the  symptom  of  pain,  in  any  por 
tion  of  the  scalp,  one  which  may  guide  us  in  looking  for  its 
cause ;  since,  if  it  is  confined  to  the  anterior  and  lateral 
aspects  of  the  head,  the  fifth  nerve  is  probably  affected  by 
some  source  of  irritation  (and  a  reference  to  the  cut  will  tell 
you  which  branch  of  the  nerve  is  distributed  to  the  seat  of 
pain),  while,  if  confined  to  the  posterior  portion  of  the  scalp, 
the  occipital  nerves  are  affected,  and  disease  of  the  spine  may 
be  suspected,  in  the  region  of  the  first  or  second  cervical  ver- 
tebrae. 

The  distribution  of  the  fifth  nerve  to  the  conjunctiva,  both 
of  the  globe  of  the  eye  and  also  of  the  lids,  exhibits,  to  a 
wonderful  degree,  the  axiom  given  you  in  the  first  lecture  of 
the  course,  as  to  the  harmony  of  action  between  the  sensory 
nerves  of  the  skin,  the  muscles  adjacent,  and  the  joints  which 
they  move  ;  since  these  parts  stand  very  much  in  the  same 
general  relation  to  each  other,  if  the  movable  point  in  the 
eyelids  be  taken  as  a  joint,  and  the  muscles  of  the  lids  as 
those  which  move  it. 


172  THE  CRANIAL  NERVES. 

An  analogy  has  been  drawn  by  a  prominent  author' 
between  a  common  two-rooted  spinal  nerve  and  a  great 
"compound  nerve  "of  the  head,  whose  sensory  root  corre- 
sponds to  the  sensory  portion  of  the  fifth  nerve,  and  whose 
motor  root  comprises  the  third,  fourth,  fifth  (its  motor 
portion),  sixth,  and  seventh  cranial  nerves,  which,  together, 
form  the  motor  root  of  this  compound  nerve.  Most  of  the 
reflex  acts  which  are  exhibited  in  the  regions  of  the  head 
and  the  upper  portion  of  the  neck  can  be  explained  by 
the  free  communication  which  exists  between  the  sensory 
root  of  this  ''compound  nerve"  and  its  different  motor 
branches. 

It  seems  useless  to  further  incorporate  such  cases,  which 
go  to  prove  that  only  by  a  thorough  familiarity  with  anat- 
omy are  we  enabled  to  explain  the  many  phenomena  which 
often  puzzle  the  practitioner ;  and  that,  if  we  will  but  use  it 
as  a  guide,  diagnosis  may  be  greatly  simplified,  and  an  easy 
remedy  often  discovered  for  the  symptoms. 

SURGICAL  ANATOMY  OF  THE   FIFTH   NERVE. 

Surgical  operations  are  often  demanded  for  the  relief  of 
those  tormenting  neuralgias  which  affect  the  branches  of  the 
fifth  nerve. 

The  simple  division  of  a  nerve  is,  at  present,  seldom  prac- 
ticed, owing  to  the  certainty  of  prompt  reunion  of  the  nerve 
divided.  Resection  of  not  less  than  two  inches  of  its  length 
is  usually  required  to  make  reunion  impossible,  or  very  re- 
mote in  point  of  time.  It  has  been  proposed  to  turn  the  pe- 
ripheral extremity  of  the  nerve  backward  after  section,  or  to 
interpose  muscle  or  fascia,  to  prevent  the  possibility  of  union.'' 
Exposure  and  stretching  of  spinal  nei-ves  for  the  relief  of  neu- 
ralgia have  been  proposed  by  Yon  Nussbaum,  but  are  not 
usually  practiced  upon  the  cranial  nerves. 

The  supra-orhital  nerve  may  be  thus  divided  : 

Pass  a  narrow  knife,  subcutaneously,  from  a  point  two  or 
three  lines  on  the  inner  side  of  the  supra-orhital  notch,  out- 

1  John  Hilton,  "  Kcst  and  Pain."  »  S.  W.  Mitchell. 


SURGICAL  AXATOMY  OF  THE  FIFTH  NERVE.  173 

ward,  until  the  point  has  passed  beyond  the  notch ;  then  turn 
the  blade  backward,  and  cut  down  to  the  bone.  To  resect 
the  nerve,  make  a  one-inch  incision  above  and  parallel  to  the 
supra-orbital  arch  ;  seize  the  cut  ends  of  the  nerve  in  the 
wound,  and  remove  it  to  the  desired  extent.' 

To  excise  the  superior  maxillary  nerne^  a  crucial  incision 
is  made  over  the  infra-orhital  foramen^  and,  by  the  use  of  a 
small  trephine,  the  anterior  wall  of  the  antrum  is  opened  so  as 
to  include  the  foramen.  The  lower  wall  of  the  infra-orbital 
canal  is  now  broken  with  a  chisel  as  far  as  the  spheno- 
maxillary fossa,  and  the  nerve  is  then  divided  at  the  fora- 
men rotundum  with  a  pair  of  scissors  sharply  curved. 
Meckel's  ganglion  is  frequently  removed  with  the  excised 
nerve.' 

To  divide  the  inferior  dental  nerve^  the  incision  may  be 
made  within  the  mouth  or  externally.  If  the  trunk  is  to  be 
removed,  before  the  nerve  enters  the  canal  in  the  lower  jaw, 
the  external  incision  is  made  from  the  sigmoid  notch  to  the 
edge  of  the  jaw.  The  parotid  gland  is  then  turned  backward, 
and  the  lower  portion  of  the  masseter  muscle  detached.  A 
section  of  bone  is  now  removed  with  a  trephine,  and  the  dental 
artery  is  tied,  in  case  it  be  wounded  ;  the  nerve  may  then 
be  divided,  and  a  half  inch  of  it,  which  will  be  found  to  be 
exposed,  resected. 

In  the  intra-huccal  operation,  the  corner  of  the  mouth  is 
held  wide  open,  and  an  incision  one  inch  in  length  is  made 
along  the  anterior  part  of  the  ramus  of  the  jaw,  through  the 
fibers  of  the  internal  pterygoid  muscle.  This  muscle  is  then 
loosened  from  the  periosteum  by  the  finger,  where  the  nerve 
can  be  easily  felt,  at  its  entrance  into  the  dental  canal,  and 
there  divided. 

THE   GANGLIA   CONNECTED   WITH   THE   FIFTH   NERVE. 

In  the  cut  which  illustrates  the  distribution  of  the  branches 
of  the  fifth  nerve  will  be  perceived  four  ganglionic  enlarge- 

^  J.  X.  Warren.  -  J.  R-  Wood. 


174  THE  CRANIAL  NERVES. 

ments,  exclusive  of  the  ganglion  of  Gasser,  which  are  con- 
nected with  the  nerve,  and  which  have  a  most  important 
function  as  regards  the  tissues  to  w^hich  these  branches  are 
distributed. 

As  you  will  notice,  the  first  is  connected  with  the  ophthal- 
mic division,  and  is  situated  within  the  orbit.  It  is  called  the 
"ophthalmic  ganglion,"  from  its  attachment;  also  the  "len- 
ticular ganglion,"  from  its  shape  ;  and  the  "  ciliary  ganglion," 
since  it  gives  off  the  ciliary  nerves  to  the  iris  and  the  muscle 
of  accommodation  of  vision.  Like  all  the  ganglia  of  the  sym- 
pathetic nerve,  it  has  a  motor  root^  a  sensory  root^  and  a  sym- 
patJietic  root^  and  it  furnishes  'branches  of  distribution  to 
neighboring  parts. 

The  second  is  called  "Meckel's  ganglion,"  after  its  discov- 
erer; and  the  "  spheno-palatine  ganglion,"  since  it  is  chiefly 
distributed  to  the  region  of  the  palate.  It  is  situated  in  the 
spheno-maxillary  fossa,  and  sends  branches  to  the  orbit, 
nose,  hard  and  soft  palate.  It  lies  in  close  relation  with  the 
superior  maxillary  nerve. 

The  third  is  called  the  "otic  ganglion."  It  lies  upon  the 
inferior  maxillary  nerve  below  the  foramen  ovale,  and  sends 
branches  to  the  two  tensor  muscles,  viz.,  the  tensor  tympani 
and  the  tensor  palati.  It  is  thus  physiologically  associated 
with  the  acts  of  hearing  and  deglutition. 

The  fourth  is  called  the  "  submaxillary  ganglion,"  since  it 
lies  above  the  submaxillary  gland.  It  is  by  means  of  the  dis- 
tribution of  the  chorda  tympani  nerve  to  this  ganglion  that 
some  physiologists  attempt  to  explain  the  apparent  effect 
which  that  nerve  has  upon  the  sense  of  taste  in  the  anterior 
two  thirds  of  the  tongue.' 

The  following  table '  will  perhaps  assist  you  in  remember- 
ing the  special  points  of  each  of  these  ganglia,  as  it  shows  the 
various  sources  of  supply  to  each,  as  well  as  branches  of  dis- 
tribution : 

^  See  previous  portion  of  this  chapter,  where  the  gustatory  nerve  is  discussed. 
*  After  Keen. 


THE  ABDUGEN8,    OR  SIXTH  NERVE. 
THE   GANGLIA   OF   THE   FIFTH   CKANIAL   NERVE. 


175 


Name. 

Situation. 

Sensory  root. 

Motor  root. 

Sympathetic 
root. 

Branches  of  distribution. 

1 

OPHTHAL- 
MIC or 
CILIAKY. 

Between  the 
optic  nerve 

and  e'xt. 

rectus. 

5th  nerve— 
Nasal 
bri»nch. 

3d  nerve. 

Cavernous 
plexus. 

To  ciliary  muscle  and 
iris. 

MECKEL8 

SPHENO- 
PALATINE. 

Spheno- 

inaaillary 

jossa. 

5th  nerve— 
Spheno-pala- 
iine  branches. 

Tth  nerve, 
through  Vidi- 
an and  large 
petrosal 
branches. 

Carotid 
PLEXUS,  by 
means  of  Vi- 
dian nerve. 

Orbital,  nasal,  naso-pala- 
t^ne,  anterior  or  largo 
palatine,  iiiiddle  or  ex- 
ternal palatine. 

Post,  or  I  Levator  palati, 
small    •<  Azygos  uvulaB, 

palatine  f  Palato-glossus. 

^ 

OTIC. 

Below  the 

J  or  amen 

ovale. 

OTH   NERVE— 

Auriculo- 
temporal 
branch. 

7th  nerve, 

through  f^mall 

petrosal. 

5th  nerve. 

through  i7it. 

pterygoid 

branch. 

Plexus  on  the 

MIDD1,E   ME- 
NINGEAL 
ARTERY. 

To  tensor  tympani  and 
tensor  palati  muscles. 

SUBMAXIL- 
LARY. 

Above  the 
suhmadcil- 
lary  gland. 

StH   NERVE— 

Lingual  or 
gustatory 
branch. 

7Tn  nerve, 
through  chor- 
da tympani 
branch. 

Plexus  on  the 

FACIAL 
ARTERY. 

To  submaxillary  gland 
and  mucous  membrane 
of  the  mouth. 

By  reference  to  the  above  table,  you  will  perceive  that  the 
]ensory  root  of  each  of  the  four  ganglia  is  derived  from  the 
yth  cranial  nerve  by  means  of  some  of  its  branches ;  that 
bhe  motor  root  is  derived,  in  three  cases  out  of  four,  from  the 
"ieventli  cranial  nerve ;  and,  finally,  that  in  every  case  is  the 
sympathetic  root  derived  from  2i  plexus  upon  some  neighbor- 
ig  blood-vessel. 


'HE  ABDUCENS,   OR   SIXTH  NERVE   (MOTOR    OCULI    EXTERNUS). 

The  apparent  origin  of  this  nerve  is  from  a  groove  between 
bhe  anterior  pyramid  of  the  medulla  oblongata  and  the  pos- 
terior border  of  the  pons  Varolii.  The  nerve  may  be  said  to 
)ossess  two  roots,  one  of  which  can  be  traced  into  the  pyra- 
midal body  of  the  medulla,  and  the  other  into  the  pons  Ya- 
'olii  itself.     This  latter  root  is  sometimes  wanting. 

Its  deep  origin  has  been  traced  by  Lockhart  Clarke  to  a 
[nucleus  in  the  gray  matter  of  the  fourth  ventricle  of  the  brain, 
on  the  outer  side  of  the  locus  cceruleus. 

This  nerve  is  purely  motor  in  its  function,  and  is  distribu- 
ted to  the  external  rectus  muscle  of  the  eye. 


176 


THE  CRANIAL  NERVES. 


The  most  careful  researches  of  Vulpian  have  as  yet  failed 
to  discover  any  decussation  of  the  deep  fibers  of  this  nerve, 
and  there  would  seem  to  be  a 
physiological  explanation  for 
the  absence  of  such  an  arrange- 
ment, since  the  two  external 
recti  muscles  are  seldom  called 
into  simultaneous  action,'  and 
the  normal  movements  of  the 
eyes  are  opposed  to  such  a  po- 
sition as  would  ensue  if  they 
should  act  in  common. 

The  sixth  nerve  anasto- 
moses with  the  sympathetic 
nerve  in  the  cavernous  sinus, 
where  it  receives  filaments  from 
both  the  carotid  plexus  and 
from  Meckel's  ganglion  ;  and  a 
few  sensory  filaments  are  said 
to  be  given  to  it  from  the  oph- 
thalmic branch  of  the  fifth  cranial  nerve  in  this  locality. 

Occasionally,  this  nerve  sends  a  filament  to  the  ophthalmic 
ganglion,  and  thus  to  the  iris,  and  it  is  claimed  by  Longet 
that  this  arrangement  (which  is  an  exceptional  one)  exists  in 
those  cases  of  paralysis  of  the  motor  oculi  nerve  in  which 
there  is  no  apparent  effect  produced  upon  the  mobility  of  the 
pupil. 

This  nerve  has  no  practical  importance  to  the  diagnostician, 
save  the  one  fact  that,  in  case  it  be  paralyzed,  the  eye  will 
present  the  condition  of  internal  strabismus ;  that  the  ap- 
parent size  of  the  objects  perceived  by  the  retina  is  magni- 
fied,^ and  that  the  head  will  be  so  deflected  as  to  avoid  the 
perception  of  double  images.' 

Tlie  explanation  of  both  of  these  effects,  as  the  result  of 

'  After  the  eyes  have  been  drawn  inward,  as  in  attempts  to  foeus  near  objects,  these 
muscles  help  to  restore  the  axes  of  vision  to  a  state  of  parallehsm. 

2  For  explanation  of  this  symptom,  the  reader  is  referred  to  page  143  of  this  volume. 

3  See  page  140  of  this  volume. 


Fig.  59. — Distribution  of  the  motor  oculi 
externtts.     (Ilirschfeld.) 

1,  trunk  of  the  motor  oculi  communis,  with 
its  branches  (2,  3,  4,  5,  6,  7) ;  8,  motor 
oculi  externtts,  passing  to  the  external 
rectus  muscle  ;  9,  filaments  of  the  motor 
oculi  externus  anastomosing  icith  the 
sympathetic  ;  10,  ciliary  nerves. 


THE  FACIAL,    OR  SEVENTH  NERVE,  177 

paresis  of  certain  ocular  muscles,  has  already  been  given  in 
the  previous  lecture  upon  the  third  cranial  nerve,  and  need 
not  be  again  repeated.  It  should  not  be  forgotten,  however, 
that  internal  strabismus  is  not  always  due  to  paralysis  of  the 
external  rectus  muscle,  but  may  indicate  a  condition  of  con- 
genital or  acquired  hyperopia,  causing  a  weakness  of  the  ex- 
ternal rectus  muscle. 


THE   FACIAL,   OR   SEVENTH  NERVE. 

This  nerve  has  its  apparent  origin  from  a  groove  between 
the  olivary  and  restiform  'bodies  of  the  medulla  oblongata, 
and,  like  the  three  preceding,  has  its  deep  origin  in  a  gray 
nucleus  in  the  floor  of  the  fourth  ventricle,  in  the  upper  half 
of  that  space  near  to  the  postero-median  fissure. '  The  fila- 
ments of  origin,  within  the  substance  of  the  medulla  oblongata, 
may  be  traced  as  a  fan-like  expansion  upon  the  floor  of  the 
fourth  ventricle,  some  of  which  terminate  in  the  gray  nucleus, 
above  described,  of  the  same  side  as  that  on  which  the  nerve 
escapes,  while  other  fibers  may  be  seen  to  decussate^  thus 
passing  to  the  nucleus  of  the  opposite  side.  No  filaments 
have  as  yet  been  satisfactorily  traced  upward  beyond  the 
limits  of  the  medulla."  This  nerve  accompanies  the  nerve  of 
hearing  throughout  the  whole  length  of  the  internal  auditory 
canal^  and  there  communicates  with  it  by  a  few  filaments.  It 
then  enters  a  curved  canal  within  the  temporal  bone,  called 
the  aqueduct  of  Fallojpius^  where  it  gives  off  the  three  petro- 
sal nerves  and  the  chorda  tympani  branch,  whose  physiologi- 
cal action  has  been  already  considered  in  connection  wdth  the 
fifth  nerve.  From  this  canal,  it  escapes  through  the  stylo- 
mastoid foramen,,  having,  before  its  exit,  given  a  tympanic 

^  Lockhart  Clarke.  An  accessory  portion  of  this  nerve — the  "  nerve  of  Wrisherg  " — 
conveys  fibers  to  it,  whose  deep  origin  may  be  traced  to  the  lateral  column  of  the  cord. 
Its  importance  is  now  being  extensively  discussed,  as  having  a  connection  with  the  chorda 
tympani  nerve. 

2  The  deep  origin  of  the  fibers  of  the  facial  nerve  seems  to  have  some  connection  with 
the  upper  portions  of  the  enccphalon  (as  shown  by  the  clinical  facts  mentioned  in  previ- 
ous pages,  when  discussing  "  crossed  paralysis  ") ;  but  little  is,  as  yet,  positively  known 
concerning  the  course  and  termination  of  these  fibers.    * 


178 


THE  CRANIAL  NERVES. 


branch  to  the  ear.'  In  the  region  of  the  stylo-mastoid  fora- 
men, it  communicates  with  five  nerves^  namely,  the  great 
auricular  (a  branch  of  the  cervical  plexus),  the  auriculo-tem- 


FiG.  60. — Superjicial  branches  of  the  facial  and  the  fifth.     (Hirschfeld.) 

1,  trunk  of  tlie  facial ;  2,  posterior  auricular  nerve  ;  3,  branch  lohich  it  receives  from  the 
cervical  plexus  /  4,  occipital  branch  ;  5,  6,  branches  to  the  mvscles  of  the  ear  ;  7,  diyas- 
iric  branches  ;  8,  branch  to  the  stylo-hyoid  mutcle  ;  9,  superior  terminal  branch  ;  10, 
temporal  branches  ;  W,  frontal  branches  ;  12,  branches  to  the  07'bicHlaris  palpebrarum  ; 
13,  nasal,  or  snboi'bital  brandies  ;  14,  buccal  branches  ;  15,  inferior  terminal  branch  ; 
16,  mental  branches;  11,  cervical  branches;  18,  superficial  temporal  nerve  (branch 
of  the  fifth);  19,  20,  frontal  nerves  (branches  of  the  fifth);  21,  22,  23,  24,  25,  26, 
27,  branches  of  the  fifth  ;  28,  29,  30,  31,  32,  branches  of  the  cervical  nerves. 

poral  (a  branch  of  the  fifth  nerve),  the  pneumogastric,  tlie 

glosso-pharyngeal,  and  the  carotid  plexus  of  the  sympathetic  ; 

and,  subsequently,  it  divides  and  is  distributed  to  the  muscles. 

The  facial  is  the  great  motor  nerve  of  the  muscles  of  the 


'  Occasionally  also  the  f  lament  of  communication  to  the  pneumogastric  nerve. 


DISTRIBUTION  OF  FACIAL  NERVE.  179 

face;  lience  the  nerve  of  expression.'     It  supplies,  in  addi- 
tion to  the  facial  muscles,  the  muscles  of  the  external  ear ; 


Fig.  61. — A  diagram  of  the  branches  of  the  facial  nerve. 

1,  main  trunk  of  nerve  in  internal  auditory  canal ;  2,  branches  of  communication  with 
AUDITORY  nerve;  3,  orificc  of  aqueduct  of  Fallopixis ;  'i,  large  petrosal  nerve;  5, 
small  petrosal  nerve  ;  6,  external  petrosal  nerve  ;  Y,  filaments  to  the  laxator  tympani 
muscles  ;  8,  chorda  ii/mpa?ii  nerve  ;  9,  stylo-mastoid  foramen  ;  IQ^postcrior  auricular 
nerve  ;  11,  filament  supplying  the  stylo  hjoid  and  digastric  muscles ;  12,  the  temporo- 
FACiAL  division  of  the  nerve  ;  13,  the  temporal  branches  ;  14,  the  malar  branches  ; 
15,  the  infra-orbital  branches;  16,  the  buccal  branches;  17,  the  snpra-maxillary 
branches;  18,  the  infra-maxillary  branches;  19,  the  cervico-facial  division;  20, 
"  intumescentia  ganglioformis '" — the  seat  of  origin  of  the  petrosal  nerves. 

three  muscles  of  the  neck,  namely,  the  stylo-hyoid,  posterior 
belly  of  the  digastric,  and  the  platysma  ;  one  muscle  of  the 
middle  ear,  the  stapedius ;  and  one  muscle  of  the  palate,  the 
levator  palati."  By  means  of  the  chorda  tympani  branch, 
it  controls  the  secretion  of  the  parotid  and  submaxillary 
glands,  and,  possibly,  the  sense  of  taste.'    By  the  large  pe- 

'  Sir  Charles  Bell. 

'^  Schiff,  1851  ;  Bernard.  Possibly  also  some  other  muscles,  by  means  of  the  lingual 
branch,  described  by  Hirschberg. 

3  Sappcy  ;  Ilirschfeld ;  A.  Flint,  Jr. ;  J.  C.  Dalton.  The  fibers  of  the  chorda  tympani 
nerve,  by  some  of  the  later  authorities,  are  said  to  arise  from  an  intermediate  nerve 
formed  by  a  branch  from  both  the  seventh  and  eighth  cranial  nerves,  and  called  the 
"portio  intermedia"  or  "nerve  of  Wrisberg." 


180  THE  CRANIAL  NERVES. 

trosal  branch,  the  levator  palati  and  azygos  uviilse  are  sup- 
plied ;  and,  by  the  small  petrosal  branch,  the  tensor  tym- 
pani  and  tensor  palati  muscles  are  furnished  with  motor 
power. 

Several  interesting  articles  have  lately  appeared  upon  the 
subject.' 

It  is  claimed  by  Vulpian  that  the  facial  nerv^e  also  con- 
tains vaso-motor  fibers^  which  are  distributed  to  the  vessels  of 
the  tongue  and  side  of  the  face. 

The  effects  of  paralysis  of  the  facial  nerve  were  first 
brought  to  professional  notice  by  Sir  Charles  Bell,  who  di- 
vided it  for  facial  neuralgia,  and  the  characteristic  deformity 
which  resulted  is  still  known  under  the  name  of  "Bell's  pa- 
ralysis." In  this  condition,  the  affected  side  loses  its  normal 
expression,  and  becomes  abnormally  smooth  on  account  of 
the  obliteration  of  the  normal  lines  and  wrinkles,  due  to  the 
action  of  the  antagonistic  muscles  on  the  healthy  side."  The 
patient  loses  all  power  of  closing  the  eye  of  the  affected  side 
even  in  sleep,  since  the  orbicularis  palpebrarum  muscle  is 
paralyzed ;  the  mouth  is  no  longer  symmetrical,  since  it  is 
drawn  toward  the  healthy  side ;  the  saliva  is  with  difficulty 
retained ;  and  the  act  of  whistling  becomes  an  impossibility, 
as  the  lips  can  not  be  systematically  governed.  This  condi- 
tion may  be  produced  by  exposure  to  severe  cold,  as  in  sleigh- 
riding  ;  by  abscess  or  tumors  of  the  parotid  region,  as  the 
result  of  the  pressure  created  ;  by  diseases  of  the  ear  or  inju- 
ries to  the  temporal  bone,  which  impede  the  free  action  of 
the  nerve ;  and  by  cranial  lesions.  It  is  particularly  impor- 
tant that  the  surgeon  should  familiarize  himself,  not  only 
with  the  situation  and  course  of  the  main  trunk  of  this 
nerve,  but  also  with  the  course  of  its  branches,  previous  to 
performing  operations  about  the  face,  or  in  the  vicinity  of 
the  mastoid  process,  and  in  the  upper  portions  of  the 
neck. 

1  Vulpian,  "Lancet,"  1878;  II.  R.  Bigelow,  *' Brain,"  1876;  E.  C.  Spitzka  "Medical 
Record,"  18  SO. 

*  Hence  the  aptness  of  the  remark  by  Romberg,  as  quoted  by  Hammond,  that  "  there 
is  no  better  cosmetic  for  elderly  ladies  than  facial  paralysis." 


DISTRIBUTION  OF  FACIAL  NERVE. 


181 


The  distribution  of  this  nerve  to  the  muscles  of  the  palate 
and  to  the  stylo-hyoid  explains  the  impairment  of  deglutition 
when  the  facial  nerve  is  paralyzed  ;  while  the  filament  to  the 
stapedius  muscle  may  create  modifications  in  the  sense  of 
hearing  under  similar  conditions. ' 


Fig.  62. — BcWs paralysis.     (Modified  from  Corfe.) 

The  following  tabulated  arrangement  of  the  branches  of 
the  seventh  nerve ""  will  possibly  prove  of  service  to  you  as  an 
aid  to  memory  during  your  student  life  ;  and,  as  a  guide  for 
reference  or  review  in  your  professional  labors,  such  tables 
are  always  of  value  : 


'  The  tensor  tympani  muscle  may  also  be  involved. 

2  Copied  from  "  The  Essentials  of  Anatomy"  :  Darling  and  Ranney,  New  York,  1880. 
14 


182 


TEE  CRAmAL  NERVES. 


TABLE  OF  THE  BRANCHES  OF  THE  FACIAL  I?^ERVE. 


Branches  of 
communication. 


Branches  of 
distribution. 


''  In  the  auditory  canal. 


\ 

In  the  aqueduct  of  Fallopius.     ■< 


At  its  exit  from  the  stylo-mas- 
toid  foramen^  with  the  fol- 
lowing nerves : 

l^  On  the  face. 

I  In  the  aqueduct  of  Fallopius. 

Near  the  stylo-mastoid  fora- 
men. 

On  the  face. 


Branch  to  auditory  nerve. 

Large   petrosal    (to    Meckel's 
ganglion). 

Small  petrosal  (to  otic  gangl'n). 

External  petrosal  (to  meningeal 
plexus). 

Tympanic  branch. 
^  Great  auricular. 

Auriculo-temporal. 
^  Pneumogastric' 
I  Glosso-pharyngeal. 
(^  Carotid  plexus. 

Branches  to  fifth  cranial  nerve 

j   Tympanic  nerve. 
\   Chorda  tympani  nerve. 
C  Posterior  auricular  nerve. 
J  Diagastric  branch. 
1  Stylo-hyoid  branch. 
[  Lingual  branch.^ 
j  Temporo-facial  nerve. 
i  Cervico-facial  nerve. 


If  you  will  look  at  this  diagrammatic  drawing  (Fig.  63), 
you  will  perceive  how  simple  is  the  arrangement  of  the 
branches  of  communication  between  the  facial  nerve  and  the 
fifth  cranial  nerve  and  its  ganglia.  While  the  drawing  is 
intended  to  be  purely  schematic,  still  it  also  illustrates  some 
of  the  anatomical  points  pertaining  to  the  course  and  forma- 
tion of  the  Vidian  nerve,  as  well  as  the  relations  of  the  clior- 
da  tympani  nerve  to  the  membrana  tympani^  as  it  passes 
through  the  middle  ear  to  reach  the  canal  of  Huguier. 

There  is  a  practical  point  pertaining  to  the  deep  origin  of 
the  fibers  of  the  facial  nerve,  which  may  often  be  of  value  in 
determining  the  seat  of  pathological  lesions  within  the  sub- 
stance of  the  brain.  In  hemiplegia,  especially  in  that  variety 
which  is  due  to  haemorrhage,  the  face  is  sometimes  affected 
upon  the  same  side  as  the  body  and  sometimes  upon  the  oppo- 
site side,  thus  being  impaired,  respectively,  either  upon  the 
side  opposite  to  the  cerebral  lesion  or  upon  the  same  side  as 
the  lesion.     To  explain  these  phenomena  theoretically,  we 


*  This  communicating  filament  is  given  off  in  the  aqueduct  of  Fallopius  as  often  as  at 
the  stylo-mastoid  foramen. 

^  Described  by  Ilirschberg.  Supplies  the  stylo-glossus  and  palato-glossus  muscles  and 
the  tongue. 


CROSSED  FACIAL  PARALYSIS, 


183 


must  suppose  that  the  facial  nerve  fibers  are  affected  by  the 
lesion  within  the  brain  before  they  decussate  (following  them 
from  within  outward),  in  case  the  face  is  paralyzed  on  the 
same  side  as  the  lesion  ;  and  that  the  decussating  fibers  are 


Fi~.  63. — A  diaf/ram  to  show  tlie  relations  between  the  facial  nerve  and  some  portions  of  the 

fifth  nei've. 

A,  Gasscrian  ganglion;  B,  ophthalmic  nerve;  C,  superior  maxillary  nerve;  D,  inferior 
maxillary  nerve  (sensory  portion) ;  E,  inferior  maxillary  nerve  (motor  portion) ;  M, 
Meckel's  ganglion;  \^  facial  nerve,  entering  the  aqveduct  of  Fallopius ;  2,  inlumcs- 
centia  ganglioformis  (an  enlargement  on  the  nerve) ;  3,  facial  nerve,  following  the 
curve  of  the  aqueduct  of  Fallopius ;  4,  facial  nerve,  escaping  from  stylo-mastoid  fora- 
men ;  5,  large  petrosal  branch,  joining  caiotid  filament  11  to  form  the  Vidian  nerve, 
and  entering  the  Vidian  canal ;  6,  stn  all  petrosal  branch,  going  to  "  otic  ranglion  "  10  ; 
7,  chorda  tympani  nerve,  escaping  from  the  canal  of  Huguier  after  winding  over  the 
upper  border  of  drum  membrane  of  ear,  9 ;  8,  gustatory  nerve,  joining  with  the  chorda 
tympani  nerve;  9,  extamal  drum  membrane  of  the  ear;  10,  otic  ganglion ;  11,  f la- 
ment from  carotid  plexus  to  form  the  Vidian  nerve ;  1 2,  the  iter  chordoe  posterius,  ad- 
mitting the  chorda  tympani  nerve  into  the  cavity  of  the  middle  ear. 


pressed  upon  or  destroyed  by  the  lesion,  in  case  the  face  be 
affected  on  the  same  side  as  the  body. 

I^ow,  it  has  been  observed  as  a  pathological  fact,  that 
when  a  lesion  involves  parts  of  the  encephalon  anterior  to  the 
pons  Varolii,  the  phenomena  dependent  upon  paralysis  of  the 
facial  nerve  are  perceived  on  the  same  side  as  the  hemiplegia  ; 
while,  if  the  lesion  be  situated  either  in  the  lower  part '  of  the 
pons  Varolii  or  below  it,  the  face  is  paralyzed  on  the  same 
side  as  the  lesion,  or  on  the  side  opposite  to  the  hemiplegia. 

'  Gubler  has  shown  that  the  facial  nerve  is  not  paralyzed  upon  the  same  side  as  the 
lesion,  if  the  injury  to  the  pons  Varolii  be  anterior  to  the  imaginary  line  drawn  through 
the  points  of  escape  of  the  trigemini. 


184  THE  CRANIAL  NERVES. 

For  this  reason,  the  occurrence  of  hemiplegia,  with  crossed 
facial  paralysis '  has  been  received  as  a  most  positive  indica- 
tion of  a  lesion  situated  upon  the  same  side  of  the  brain  as 
that  of  the  face,  and  either  within  the  substance  of  the  pons 
Varolii  or  in  parts  of  the  encephalon  posterior  to  it.  Such 
clinical  facts  as  these  seem  positively  to  indicate  that  some  of 
the  deep  fibers  of  the  facial  nerve  pass  upward  into  the  cere- 
brum^ and  that  the  decussation  of  the  filaments  of  origin 
within  the  floor  of  the  fourth  ventricle  is  of  little  physiological 
importance  compared  to  these  other  fibers  ;  but,  unfortunate- 
ly, no  anatomical  investigations  have,  so  far,  discovered  fibers 
of  this  nerve  which  could  ba  clearly  demonstrated  as  passing 
upward  beyond  the  pons  Yarolii. 

It  has  been  often  noticed  by  different  observers  that,  in 
case  the  facial  nerve  was  paralyzed,  the  uvula  and  soft  palate 
were  affected  and  drawn  toward  the  healthy  side  by  the  an- 
tagonistic muscles,  whose  motor  power  remained  unimpaired. 
Later  investigation  has  shown,  however,  that  this  affection  of 
the  palate  only  occurs  in  those  cases  of  paralysis  due  to  im- 
pairment of  the  facial  nerve  within  the  aqueduct  of  Fallopius, 
or  from  some  cranial  lesion  which  affects  its  filaments  of 
origin.'' 

The  experiments  of  Bernard  seem  to  demonstrate  that  the 
facial  nerve^  and  not  the  glosso-pharyngeal  alone,  is  con- 
nected with  movements  of  the  xelum  palati,  but  not  with  the 
movements  of  the  pillars  of  the  fauces.  The  construction  of 
the  small  petrosal  branch,  however,  being  composed  partly  of 
fibers  derived  from  the  glosso-pharyngeal  nerve,  may  still 
justify  a  doubt  upon  this  point. 

Hirschfeld  describes  a  small  filament,  which  the  facial 
nerve  gives  off  soon  after  it  emerges  from  the  stylo-mastoid 
foramen,  ''the  lingual  branch^'"'  which  is  distributed  to  the 
tongue  and  to  the  stylo-glossus  and  palato-glossus  muscles. 

'  A  term  used  to  cover  those  terms  of  paralysis  where  the  face  is  paralyzed  on  the 
side  opposite  to  the  side  of  the  body  affected.     See  diagram  on  page  60. 

*  The  petrosal  nerves,  which  carry  the  motor  fibers  to  these  muscles,  must  be  impaired 
to  cause  any  deflection  of  the  palate. 

^  See  tabic  on  page  182. 


COMMUNICATIONS  OF  FACIAL  NERVE.  185 

This  may  possibly  exi3lain  the  observation  of  Bernard :  that 
paralysis  of  the  facial  nerve,  after  section,  produces  a  devia- 
tion of  the  tip  of  the  tongue;  and  the  same  effect  has  been,  at 
fifferent  times,  recorded  as  the  result  of  paralysis  of  the  facial 
erve  from  intra-cranial  causes. 
BKAXCHES  OF  C0MMUKICATI0:N"  OF  THE  FACIAL  J^TEKVE. 
Some  of  the  branches  of  communication  which  are  given 
uff  by  the  facial  nerve,  to  join  with  other  nerves,  or  to  be  dis- 
tributed to  ganglia,  are  of  physiological  importance.  Thus 
the  levator  palati  and  the  azygos  uvuIcb  muscles  derive  their 
motor  power  from  the  large  petrosal  branch  after  it  enters 
Meckel's  ganglion;'  while  the  palato-glossus  and  palato- 
pJiaryiigeus  muscles  probably  derived  their  motor  power 


Fig.  64. — Chorda  tympani  nerve.    (Hirschfeld.) 

1,  2,  3,  4,  facial  nerve  passing  thrcupjh  the  aqueductus  Fallopii ;  5,  ganglioform  enlarge- 
ment ;  6,  great  petrosal  nerve ;  7,  spheno-palatine  ganglion  ;  8,  small  petrosal  nerve ; 
9,  chorda  tympani ;  10,  11,  12,  13,  various  branches  of  the  facial ;  14,  14, 15,  glosso- 
pharyngeal nerve. 

from  the  communicating  filament  between  the  facial  and  the 
glosso-pharyngeal  nerves,  as  shown  by  Longet.  This  distribu- 
tion explains,  in  part,  why  more  or  less  difficulty  is  perceived 
in  degliitUlon  after  division  or  paralysis  of  the  facial  nerve, 
and  still  more  clearly  why  the  pronunciation  of  certain  words 
becomes  impaired,  and  the  expulsion  of  mucus  from  the  back 

^  Gray,  Quain,  Sappey,  and  others. 


186 


THE  CRANIAL  NERVES, 


portion  of  the  mouth  and  from  the  pharynx  is  an  act  of 
extreme  difficulty. 

The  communication  of  the  cervical  plexus  with  the  poste- 
rior auricular  branch  of  the  facial  affords  sensory  filaments 
to  the  parts  over  the  muscles  which  that  nerve  supplies. 

The  filament  of  communication  between  the  facial  and  the 
auditory  nerves  enables  the  muscle  of  the  middle  ear  supplied 
by  the  facial '  to  act  in  harmony  with  the  acoustic  apparatus  ; 
while  the  communication  between  the  fifth  nerve  and  the 
facial  enables  the  latter  to  follow  that  general  axiom  ^  of 
nerve  distribution  by  which  the  skin  over  the  insertion  of 


Fig.  65. — A  diagram  to  shoio  the  course  of  the  large  and  small  petrosal  nerves  and  the 

Vidian  nei'ves. 

A,  otic  ganglion  ;  B,  Meckel's  ganprlion ;  C,  petrous  portion  of  the  temporal  bone  ;  D,  pe- 
trotts  portion  of  the  temporal  bone  (its  apex  corresponding  to  the  carotid  canal  at 
the  base  of  the  skull) ;  E,  petrous  portion  of  the  temporal  bone  (its  base  correspond- 
ing to  the  external  auditory  meatus) ;  F,  petrous  portion  of  the  temporal  bone  (its 
superior  border,  separating  the  middle  and  posterior  fossae  of  the  skull);  1,  the 
facial  nerve  entering  the  petrous  portion  of  the  temporal  bone  by  means  of  the  "  me- 
atus auditorius  internum  ^^  ;  2,  the  facial  nerve  following  the  curve  of  the  ''aqueduct 
of  Fallopius";  3,  i\\c  facial  nerve  escaping  from  the  temporal  bone  by  means  of  the 
"  stylo-mastoid  foramen" ;  4,  the  large  petrosal  nerve,  escaping  into  the  cavity  of  the 
cranium  by  means  of  the  "  hiatus  Fallopii " ;  5,  the  small  petrosal  nerve,  escaping  into 
the  cavity  of  the  cranium  by  a  foramen  of  its  own ;  6,  the  '■'■  foramen  basis  cranii," 
affording  passage  for  the  largo  petrosal  nerve  out  of  the  cranium  ;  7,  the  "  foramen 
ovale,"  affording  passage  for  the  small  petrosal  nerve  out  of  the  cranium,  and  thus 
to  the  otic  ganglion  ;  8,  a  filament  from  the  carotid  plexus  of  the  sympathetic  nerve, 
joining  the  large  petrosal  nerve  to  form  the  Vidian  nerve  ;  9,  the  Vidian  canal,  trans- 
mitting the  Vidian  nerve  to  MeckcVs  ganglion,  B;  10,  the  Vidian  nerve. 

muscles  is  supplied  by  the  same  nerve  as  the  muscles  them- 
selves. 

The  communication  between  the  facial  nerve  and    the 

'  The  stapedius.       ^  mnon,  *'  Rest  and  Pain."    See  also  page  12  of  this  volume. 


COMMUNICATIONS  OF  FACIAL  NERVE.  187 

pneumogastric  might  at  first  seem,  to  tlie  casual  reader,  one 
of  accident,  rather  than  of  design,  on  the  part  of  the  Creator ; 
but,  when  we  consider  how  intimately  the  respiratory  func- 
tions and  the  movements  of  the  face  are  associated  with  each 
other,  the  design  at  once  becomes  evident.  Paralysis  of  the 
muscles  which  dilate  the  nostrils  has  been  shown  to  have  a 
marked  effect  upon  respiration  through  the  nostril ;  and,  in 
the  horse,  which  can  only  breathe  through  the  nose,  the  effect 
of  division  of  both  of  the  facial  nerves  is  to  produce  death 
from  suffocation,  .  since  the  nostrils  collapse.  It  was  this 
synchronism  between  the  movements  of  the  nostrils  and  the 
respiratory  act  that  first  led  Sir  Charles  Bell '  to  regard  the 
facial  nerve  as  the  one  which  presided  over  the  function  of 
respiration,  and  is  still  often  called  one  of  the  "respiratory 
nerves  of  Bell^ 

A  case  is  reported  by  this  famous  investigator  where  a 
patient,  afflicted  with  unilateral  facial  paralysis,  was  obliged 
to  lie  upon  the  sound  side,  and  to  hold  the  paralyzed  nostril 
open  with  the  fingers,  in  order  to  breathe  with  comfort'' 

The  distribution  of  the  facial  nerve  to  the  muscles  of  the 
nose  creates  an  impairment  of  the  sense  of  smell^^  when  that 
nerve  is  injured,  since  the  free  entrance  of  air  is  interfered 
with.  The  act  of  sniffing^  which  requires  for  its  complete 
performance  a  dilated  nostril,  is  rendered  almost  if  not  quite 
impossible,  and  thus  a  contact  of  odoriferous  substances  with 
the  mucous  membrane  of  the  upper  nasal  chambers  is  me- 
chanically interfered  with,  and  acute  jDerception  of  smell  em- 
barrassed. 

BRANCHES   OF   DISTRIBUTIOJT   OF  THE   FACIAL  KERVE. 

The  motor  branches  of  the  facial  to  the  muscles  of  the  ear 
are  of  more  importance  in  animals  than  in  man,  since  the  ear 
in  the  animal  becomes  capable  of  perceiving  sound  with  acute- 
ness  only  by  a  change  in  its  relative  position  to  the  head. 

The  stylo-hyoid  and  the  posterior  helly  of  the  digastric 
muscles  exhibit  again  the  influence  of  the  facial  nerve  upon 

^  "  Lectures  on  the  Nerves."  ^  Qp^  cit.  ^  A.  Flint,  Jr.,  op,  cit. 


188  THE  CHAXIAL  JSFERVES. 

the  act  of  deglutition  ;  and  the  same  remark  will  apply  to  the 
stylo-glossus  muscle. 

When  the  facial  nerve  has  passed  through  the  parotid 
gland,  the  two  branches  distributed  to  the  face,  viz.,  the  tem- 
poro-faclal  and  the  cervico-facial^  become  not  only  motor  in 
their  function,  but  are  also  supplied  with  sensory  filaments 
from  their  communication  with  other  nerves  ;  so  that  some  of 
their  terminal  filaments  are  distributed  to  the  integument  of 
the  face,  as  well  as  those  derived  from  the  fifth  cranial  nerve^ 
which  would  not  be  the  case  were  the  nerve  not  so  supplied 
with  sensory  nerve  fibers. 

The  filament  of  the  facial  nerve  which  supplies  the  platys- 
ma  muscle  affords  a  beautiful  example  of  the  fact  that  the 
nervous  supply  of  the  general  muscular  system,  if  carefully 
studied,  constantly  teaches  us  points  of  great  physiological 
value  as  to  the  function  of  individual  muscles,  since,  in  the 
expression  of  melancJioly,^  and  in  the  typical  countenance  of 
thoracic  and  abdominal  diseases,"  the  platysma  muscle  plays  a 
most  important  part,  and  is  therefore  supplied  by  the  nerve 
of  expression. 

Again,  the  muscles  of  the  region  of  the  mouth  are  impor- 
tant agents  in  the  prehension  of  food  (especially  so  in  animals, 
who  often  can  not  eat  when  the  lips  are  paralyzed),  and  should 
properly  be,  in  some  way,  connected  with  the  muscles  of  mas- 
tication (chiefly  supplied  by  the  fifth  nerve),  and  those  of 
deglutition  (supplied  by  the  facial  and  the  glosso-pharyngeal 
nerves) ;  hence,  the  facial  nerve  is  afforded  communicating- 
branches  with  both  t^Q  fifth  and  the  glosso-pharyngeal  nerves. 

One  of  the  muscles  of  the  face,  the  buccinator^  which  is 
supplied  exclusively  by  the  facial  nerve,  plays  a  most  impor- 
tant part  in  mastication  as  well  as  in  expression  ;  hence,  when 
the  facial  nerve  is  paralyzed,  the  cheek  can  no  longer  force 
the  food  between  the  teeth,  and  a  tendency  toward  accumula- 
tion of  food  within  the  cheek  of  the  affected  side  becomes  so 

*  Carpenter,  op.  cit. 

'  Sir  Charles  Bell,  "  Anatomy  of  Expression."  See,  also,  article  by  the  author,  "  The 
Human  Face ;  its  Modifications  in  Health  and  Disease,  etc.,"  "  New  York  Med.  Jour.," 
September,  1880. 


I 


I 


PHYSIOLOGY  OF  THE  FACIAL  NERVE.  189 

distressing  to  the  patient  that  the  fingers  are  frequently  em- 
ployed, during  attempts  at  mastication  of  the  bolus,  to  force 
the  food  between  the  jaws  by  pressure  upon  the  external  por- 
tion of  the  face.' 

The  value  of  this  muscle  in  expression  is  made  manifest  in 
those  acts  where  the  cheek  is  either  inflated  with  air,  or  where 
it  is  drawn  inward,  thus  indicating  the  states  of  emacia- 
tion or  extreme  hunger.  Much  of  the  success  of  a  comedian 
often  depends  ui^on  the  control  which  he  possesses  over  the 
buccinator  muscle.  When  t^Qfaxiial  nerve  upon  both  sides  is 
paralyzed,  mastication  is  almost  as  much  impaired  (on  account 
of  the  buccinator  muscles)  as  if  the  inferior  maxillary  nerve 
was  destroyed. 

The  flaccidity  of  the  buccinator  muscle  in  "Bellas  paraly- 
sis "  accounts  for  the  peculiar  puffing  movement  of  the  cheek 
which  accompanies  each  act  of  expiration ,  giving  to  the  face 
an  appearance  similar  to  that  noticed  when  puffing  of  a  pipe 
is  attempted  ;  while,  in  those  rare  cases  where  the  facial  nerve 
is  paralyzed  upon  both  sides,  the  face  assumes  a  condition 
which  is  remarkable  for  the  entire  absence  of  expression,  and 
which  can  only  be  compared  to  the  effect  of  covering  it  with  a 
mask. 

Many  of  the  muscles  of  the  face  are  of  value  as  guides  in 
diagnosis^  since,  in  certain  types  of  disease,  some  parts  of 
the  face  are  more  affected  than  others.'  This  subject,  how- 
ever, is  too  complicated  to  be  hastily  reviewed,  and  it  has  suffi- 
cient value  to  merit  its  special  consideration. 

It  may  be  perceived,  by  reference  to  the  diagrammatic  rep- 
resentation of  the  branches  of  the  facial  nerve,  that  the  tem- 
poro-facial  branch  animates  all  of  the  muscles  of  the  upper 
part  of  the  face,  while  the  cervico-facial  branch  supplies  the 
lower  region  of  the  face  and  portions  of  the  neck."  This  ex- 
plains why,  after  the  temporo-facial  branch  has  been  divided, 

^  A.  Flint,  Jr.,  op.  cit. 

2  See  article  by  the  author  on  *'  The  Human  Face ;  its  Modifications  in  Health  and 
Disease,  and  its  Value  as  a  Guide  in  Diagnosis : "  "New  York  Med.  Jour.,"  December, 
1880. 

^  Sec  page  HQ  of  this  volume. 


190  THE  CRANIAL  NERVES. 

as  has  occurred  in  operations  upon  the  cheek,  the  eye  stands 
wide  open  even  during  sleep ;  the  lower  lid  becomes  everted 
from  traction  of  the  parts  below,  and  also  from  the  effect  of 
gravity ;  the  occipito-frontalis  and  corrugator  supercilii  can 
no  longer  make  either  transverse  or  perpendicular  wrinkles 
upon  the  forehead  ;  and  the  upper  portion  of  the  face  is  ab- 
normally smooth  and  passive,  while  the  lower  portion  pre- 
serves all  its  normal  power  of  movement. 

Should  the  eervico-facial  branch  become  alone  impaired, 
the  power  of  prehension  of  food  by  the  lips  is  arrested,  the 
action  of  the  buccinator  in  mastication  is  s'topped,  and  that 
process  is  proportionately  interfered  with  ;  the  digastric  and 
stylo-Jiyoid  muscles  are,  however,  not  paralyzed,  since  the 
special  branches  to  those  muscles  are  given  off  above  the  ori- 
gin of  this  branch,  and  thus  deglutition  is  not  embarrassed. 

CLIN^ICAL   POIISTTS   AFFORDED   BY  THE   FACIAL   NERVE. 

The  diseases  which  affect  the  facial  nerve  may  produce 
the  different  varieties  of  facial  spasm  and  paralysis ;  the 
former  being  the  result  of  some  lesion  which  creates  simply 
irritation,  while  the  latter  indicates  some  existing  pressure  or 
degeneration,  which  impedes  the  free  action  of  the  nerve. 

SPASM  OP  THE  MUSCLES  OF  THE   FACE. 

In  a  class  of  cases,  by  no  means  infrequent,  facial  spasm  is 
perceived,  to  a  greater  or  less  degree,  as  the  result  of  some 
cause  of  irritation  to  the  nerve  filaments  of  the  trunk  of  the 
facial  nerve,  or  to  some  of  its  branches.  These  mimic  spasms, 
or  ''  convulsive  tic,"  are  dependent  upon  an  hereditary  ten- 
dency, in  some  mstances ;  since  reported  cases  exist  where 
the  second  generation,  and  even  the  third,  has  manifested  the 
symptoms  of  facial  spasm.  We  also  meet  this  condition  as  an  ■ 
accompaniment  of  epilepsy,  eclampsia,  hysteria,  tetanus,  and 
chorea  ;  again,  in  certain  mental  diseases,  where  the  brain  or 
its  investing  membranes  are  affected  ;  and,  finally,  we  see  it 
developed  under  extraordinary  periods  of  excitement. 

Cases  are  on  record  where  simple  exposure,  wounds  of  the 


BELL'S  PARALYSIS.  191 

face,  and  pressure  upon  the  peripheral  filaments  of  the  facial 
nerve  have  resulted  in  facial  spasm.  Perhaps  this  condition 
is  most  frequently  met  with  as  an  evidence  of  some  reflex  act, 
excited  through  some  other  cranial  nerves  ;  hence  we  find  it 
associated  with  such  causes  of  irritation  as  caries  of  the  teeth, 
periostitis,  inflammatory  affections  of  the  eyeball,  lids,  or  con- 
junctiva. Remak  reports  a  case  where  a  diseased  condition 
of  the  brachial  plexus  caused  spasms  to  start  in  the  hand  and 
progress  along  the  side  of  the  neck  to  the  face,  again  illus- 
trating the  reflex  character  of  the  disease. 

It  is  such  cases  as  these  latter  that  often  test  the  ana- 
tomical knowledge  of  the  diagnostician,  since  a  command  of 
the  various  anastomoses  of  nerves  often  enables  the  skilled 
anatomist  to  detect  the  seat  of  irritation  far  from  the  apparent 
seat  of  disease,  and  thus  to  obviate  a  distressing  condition  by 
some  simple  medicinal  or  surgical  remedy. 

The  spasms  of  the  facial  muscles  may  assume  either  the 
tonic  or  clonic  character.  '  The  former  variety  is  observed  in 
such  conditions  as  tetanus,  the  late  rigidity  of  paralyzed  mus- 
cles, and  the  irritation  following  upon  severe  exposure  and 
too  intense  faradization  ;  while  the  latter  are  the  most  com- 
mon, and  result  in  those  convulsive  twitchings  of  the  forehead, 
eyes,  eyelids,  nose,  mouth,  cheeks,  and  tongue,  which  pro- 
duce the  most  extreme  and  often  ludicrous  distortion  of  the 
features.  I  have  known  such  clonic  spasms  of  the  face  to 
be  produced  by  the  irritation  of  worms  in  the  intestine  in 
children,  and,  in  one  case,  to  follow  uterine  disease  in  an 
adult.  A  peculiarity  of  these  spasms  is,  that  certain  muscles 
seem  to  contract  in  a  regular  sequence  or  rhythm,  and  that, 
although  the  contraction  may  be  prolonged  and  severe,  no 
fatigue  is  usually  complained  of  by  the  patient. 

PARALYSIS   OF  THE   MUSCLES   OF  THE   FACE. 

The  general  appearance  of  a  sufferer  from  a  well-marked 
attack  of  ''Bell's  paralysis"  has  already  been  depicted  in  a 
cut,'  and  described  in  the  preceding  text,  under  the  effects 

^  Sec  page  181  of  this  volume. 


192  THE  CRANIAL  NERVES. 

of  section  of  the  facial  nerve ;  but  many  points  of  practical 
value  pertain  to  this  condition  which  have  not  as  yet  been 
mentioned,  and  which  help  greatly  in  making  a  diagnosis  as 
to  the  exciting  cause  and  the  seat  of  the  existing  lesion.  The 
symptoms  produced  by  any  impairment  to  the  free  action  of 
the  facial  nerve  vary  to  a  marked  extent  with  the  degree  of 
the  paralysis,  and  the  individual  branches  which  may  be  in- 
volved ;  and  distinctions  between  the  various  forms  of  facial 
paralysis,  met  with  in  a  large  clinical  field,  have  been  devel- 
oped, by  the  investigations  of  Romberg,  from  those  general 
propositions  first  advanced  by  Bell. 

In  studying  the  types  of  facial  paralysis,  we  may  start 
with  advantage  by  reviewing  the  different  groups  which  are 
clinically  recognized.  These  may  be  enumerated  as  the  intra- 
cranial ;  the  auditory  (where  the  existing  lesion  is  confined 
to  the  interior  parts  of  the  temporal  bone) ;  the  rlieumatic  ; 
the  traumatic ;  Wv^  syphilitic ;  and,  finally,  the  dipTitJieritic 
form.  We  may  also  have  the  paralysis  confined  to  one  side 
of  the  face,  the  unilateral^  or,  affecting  both  sides  of  the 
face,  the  bilateral^  or  facial  diplegia. 

In  the  intra-cranial  form  of  facial  paralysis,  the  lesion  of 
the  brain  is  usually  confined  either  to  the  base,  or  to  the  pons 
Varolii.  If  the  pons  Varolii  is  affected,  the  facial  nerve  will 
not  be  alone  involved,  as  a  rule,  but  a  partial  or  complete 
hemiplegia  will  usually  exist,  which  will  be  on  the  same  side 
of  the  body  as  the  facial  paralysis,  provided  the  upper  (an- 
terior) half  of  the  pons  is  the  seat  of  disease,  but  on  the  side 
opposite  to  the  facial  paralysis  (crossed  paralysis'),  if  the 
lower  (posterior)  part  of  the  poiis  is  affected.  There  is,  per- 
haps, no  point  in  the  anatomy  of  the  encephalon  which  is  of 
more  certain  value  to  the  diagnostician  than  the  fact,  first 
pointed  out  by  Gubler,  that  a  line  drawn  transversely  across 
the  pons  Varolii  at  the  points  of  escape  of  the  trigemini 
marked  the  spot  of  probable  decussation  of  fibers  of  the  facial 
nerve ;  so  that,  if  a  lesion  be  anterior  to  this  line,  the  facial 

^  For  definition  of  this  term  and  the  various  types  met  witb,  see  page  59  of  this 
volume. 


CAUSES  OF  BELL'S  PARALYSIS.  I93 

paralysis  will  correspond  to  the  hemiplegia,  but,  if  behind 
that  line,  the  condition  of  ''crossed  paralysis"  of  the  facial 
and  body  type  will  be  produced.  A  point  of  some  diagnostic 
value  in  the  detection  of  intra-cranial  lesions,  by  means  of 
the  facial  nerve,  is  afforded  by  the  degree  of  the  facial  paraly- 
sis, since  it  is  usually  complete  if  caused  by  lesions  of  the 
pons  Varolii  or  by  the  pressure  of  tumors  of  the  base  of  the 
cerebrum. 

The  second  form  of  facial  paralysis,  viz.,  that  dependent 
upon  some  abnormal  condition  within  the  temporal  hone, 
is  liable  to  follow  suppuration  or  haemorrhage  within  the 
aqueduct  of  Fallopius ;  scrofulous  caries  of  the  temporal 
bone ;  local  degeneration  of  the  nerve  within  the  aqueduct 
of  Fallopius  ;  local  pressure  upon  the  nerve  from  tumors, 
etc.;  and  traumatisms  of  all  kinds,  of  sufficient  intensity  to 
injure  the  deeper  parts  or  to  directly  involve  the  nerve 
itself. 

If  you  will  recall  the  anatomy  of  the  facial  nerve  within 
the  aqueduct  of  Fallopius,  and  the  branches  which  are  given 
off  in  that  canal,  you  will  be  better  able  to  appreciate  the 
points  afforded  by  this  anatomical  knowledge  in  the  diag- 
nosis of  the  seat  of  a  lesion  which  is  causing  facial  paraly- 
sis. We  have  already,  in  connection  with  the  effects  of 
section  of  the  facial  nerve,  mentioned  the  facial  deformity 
which  ensues ;  and  the  same  description  will  answer  for  the 
effects  of  disease  of  the  nerve,  or  pressure  upon  it,  after  it 
has  escaped  from  the  stylo-mastoid  foramen.  But  the  symp- 
toms to  which  I  now  propose  to  call  your  attention  are  not 
included  in  that  description,  since  they  are  due  to  branches 
which  are  given  off  by  the  facial  nerve  before  it  escapes  from 
the  temporal  bone  ;  although  the  same  facial  deformity,  and 
all  the  evidences  of  impairment  of  the  nerve  on  the  distal 
side  of  the  stylo-mastoid  foramen,  will,  of  necessity,  be  also 
present. 

If  the  lesion  be  situated  above  the  point  of  origin  of  the 
chorda  tympani,  but  on  the  distal  side  of  the  petrosal  nerves, 
the  sense  of  taste  wiU  probably  be  affected  on  the  correspond- 


194  THE  CRANIAL  NERVES. 

ing  side  of  the  anterior  two  thirds  of  the  tongue ; '  but  the 
sense  of  taste  is  not,  as  a  rule,  abolished,  although  it  is 
greatly  diminished  in  acuteness.  How  this  nerve  affects  the 
sense  of  taste,  and  the  various  experiments  which  have  been 
recorded  concerning  it,  will  be  found  by  reference  to  preced- 
ing pages." 

If  the  lesion  of  the  facial  nerve  be  situated  behind  the 
ganglionic  enlargement  from  which  the  three  petrosal  nerves 
arise,  the  patient  will  reveal  a  depression  of  the  arch  of  the 
palate  upon  the  affected  side ;  thus,  it  will  be  seen  to  hang 
lower  than  the  healthy  side,  and  to  approach  a  straight  line 
along  its  free  edge,  rather  than  that  of  a  marked  curve,  as  in 
health.  This  is  due  to  the  paralysis  of  the  levator  palati 
muscle,  which  is  supplied  with  motor  power  from  Meckel's 
ganglion,  through  the  large  petrosal  nerve.  In  addition  to 
this  deformity,  the  soft  palate  is  drawn  toward  the  unaffected 
side  by  the  tensor  tympani  muscle,  since  the  same  muscle 
of  the  paralyzed  side  is  no  longer  capable  of  acting,  as  it  is 
supplied  by  the  small  petrosal  nerve.  The  distribution  of  the 
small  petrosal  nerve  to  the  otic  ganglion  still  further  explains 
why,  in  this  type  of  cases,  the  secretion  of  the  parotid  gland 
of  the  affected  side  is  diminished ;  while  the  intimate  asso- 
ciation of  the  chorda  tympani  nerve  with  the  submaxillary 
gland  accounts  for  deficient  secretion  from  that  source. 

It  has  been  observed  that  the  sense  of  hearing  becomes  ex- 
cessively acute^  when  the  facial  nerve  is  affected  on  the  proxi- 
mal side  of  the  point  of  origin  of  the  petrosal  nerves.  This 
may  possibly  be  due  to  the  paralysis  of  the  tensor  tympani 
muscle,  as  suggested  by  Landouzy,  since  that  muscle  is  sup- 
plied with  motor  power  by  a  filament  derived  from  the  otic 
ganglion  ;  although  the  investigations  of  Brown- Sequard  seem 
to  point  to  a  vaso-motor  spasm  of  the  internal  ear,  resulting 
in  a  condition  of  hypersesth^sia  of  the  acoustic  nerve. 

The  third  form  of  facial  paralysis  occurs  in  connection 

^  The  reader  is  referred  to  those  pages  in  which  the  gustatory  branch  of  the  fifth 
nerve  is  discussed,  since  authorities  differ  as  to  the  value  and  interpretation  of  this  symp- 
tom. 

'  See  page  160  of  this  voUimo. 


CAUSES   OF  BELVS  PARALYSIS  I95 

with  tlie  rheumatic  diathesis.  It  is  well  known  that  the  in- 
fluence of  cold,  which  is  particularly  liable  to  favor  rheu- 
matic manifestations,  is  more  keenly  felt  in  the  region  of  the 
cheek  and  eyelids,  as  showTi  by  Weber ;  and  the  experiments 
of  Wachsmuth,'  upon  the  effect  of  cold  upon  the  vaso-motor 
fibers  in  the  region  of  the  stylo-mastoid  foramen,  also  point 
to  the  retardation,  or,  possibly,  the  entire  suppression,  of  the 
blood  supply  to  the  facial  nerve,  as  the  explanation  of  this 
type  of  paralysis.  A  mild  form  of  periostitis  in  the  bony 
canals,  through  w^hich  the  different  branches  of  the  facial 
nerve  pass,  may  also  occur  in  the  rheumatic  type  as  an  excit- 
ing cause. 

The  traumatic  types  of  facial  paralysis  may  involve  the 
entire  nerve  or  only  individual  branches.  Its  symptoms, 
therefore,  somewhat  depend  upon  the  situation  and  extent  of 
the  injury.  It  has  been  known  to  follow  severe  contusions  of 
the  face,  cheek,  or  neck,  incisions  made  by  the  surgeon,  saber 
cuts  and  gunshot  wounds,  the  compression  exerted  by  the 
forceps  during  delivery,  the  pressure  of  growing  tumors,  sup- 
puration within  the  parotid  gland  or  lymphatics  of  that 
region,  and  the  pressure  caused  by  extensive  or  deep  cica- 
trices. This  type  of  paralysis  is  often  extremely  obstinate 
and  of  long  duration,  and  may  be  permanent ;  since  the  nerve 
may  have  undergone  changes  in  its  structure  or  the  muscles 
may  have  become  impaired. 

In  syphilis,  facial  paralysis  is  sometimes  developed.  It 
may  thus  indicate  the  formation  of  intra-cranial  tumors  or 
meningeal  exudations,  which  either  press  upon  the  nerve 
trunk  or  interfere  with  its  fibers  of  origin.  It  may  also  be  an 
evidence  of  extra-cranial  lesions,  such  as  periostitis  of  the 
mastoid  region,  tumors  of  the  facial  or  cranial  bones,  or  sup- 
puration dependent  upon  caries  or  necrosis  of  the  temporal 
bone  (if  the  entire  nerve  be  affected),  or  of  some  of  the  facial 
bones,  if  individual  branches  only  show  evidences  of  pressure. 

Cases  are  on  record  where  the  symptoms  of  facial  paraly- 
sis have  followed  an  attack  of  diphtheria.     This  is  but  one  of 

1  As  quoted  by  Rosenthal. 


196  THE  CRANIAL  NERVES. 

the  various  forms  of  paralysis  which  are  frequently  observed 
as  sequelae  of  this  peculiar  blood  poison. 

It  may  be  well  to  hastily  review  the  principal  complica- 
tions which  are  most  frequently  observed  in  connection  with 
facial  paralysis.  These  have  a  special  importance  to  the  sci- 
entific practitioner  in  enabling  him  to  diagnose,  not  only  the 
condition  of  the  patient,  but  also  the  seat  of  the  existing 
lesion. 

We  have  considered  the  effects  of  lesions  within  the  aque- 
duct of  Fallopius.  These  may  create  (in  addition  to  those  of 
the  facial  muscles)  symptoms  referable  to  the  impairment  of 
the  chorda  tympani  nerve  (see  page  193),  of  the  petrosal  nerves 
(see  page  194),  acoustic  manifestations,  or  an  effect  upon  the 
salivary  secretions. 

Intra-cranial  lesions  usually  cause  destruction  of  the  mo- 
tor power  of  the  entire  nerve,  and,  therefore,  of  all  of  its 
branches ;  hence,  we  are  liable  to  have  all  of  the  previous 
symptoms  present,  as  well  as  those  of  facial  deformity. 

Special  branches  of  the  nerve  may  be  individually  para- 
lyzed, and  thus  produce  symptoms  referable  only  to  those 
parts  in  which  the  motor  power  is  deficient.  The  anatomy  of 
the  separate  branches,  as  shown  in  the  cuts  on  previous 
pages,  will  help  you  to  understand  the  special  symptoms 
which  an  impairment  of  any  one  branch  would  produce. 

The  condition  of  Mlateral  facial  paralysis,  or  '-'facial 
dijplegia^^^  is  a  rare  form  of  disease.  It  implies  some  form  of 
pressure  or  degeneration,  which  shall  affect  the  nerve  of  each 
side  simultaneously  ;  hence  it  may  accompany  a  lesion  situ- 
ated in  the  anterior  half  of  the  pons,  which  crosses  the  median 
line  ;  an  exostosis  of  the  interior  surface  of  the.  basilar  process 
of  the  occipital  bone  ;  an  intra-cranial  aneurism  ;  and  the  pres- 
ence of  excessive  meningeal  exudation  at  the  base  of  the  brain. 
It  sometimes  accompanies  the  condition  of  labio-glosso-pha- 
ryngeal  paralysis  (Duchenne's  disease),  provided  the  lesion  ex- 
tends so  as  to  involve  the  nuclei  of  origin  of  the  facial  nerves  ; 
and  is  occasionally  met  with  in  the  course  of  certain  chronic 
cerebral  diseases.     Jaccoud  claims  that  the  spontaneous  atro- 


CAUSES   OF  FACIAL  DIPLEGIA.  I97 

phy  of  both  facial  nerves  can  occur  without  an  exciting  cause 
of  a  local  character  being  detected  ;  and  the  same  opinion  is 
maintained  by  Pierreson/  who  found  a  hyperplasia  of  the 
connective  tissue  of  the  nerve  and  the  development  of  amy- 
loid corpuscles  to  constitute  the  pathological  changes. 

I  This  type  of  paralysis  may  be  due  to  peripheral  causes, 
such  as  exposure  to  intense  cold,  as  in  sleigh-riding,  rheu- 
matic inflammation  of  the  nerves,  and  diseases  of  the  petrous 
portion  of  the  temporal  bones  (necrosis,  caries,  syphilitic 
Otitis,  suppurative  inflammation  of  the  middle  ear,  etc.). 
The  experiments  of  Schiff  upon  animals  in  whom  both 
facial  nerves  had  been  divided,  and  the  investigations  of  Trous- 
seau, Wachsmuth,"  and  Davaine,  have  helped  to  clear  up  the 
effects  of  this  double  lesion,  and  to  render  its  diagnosis  from 
Duchenne's  disease  more  positive  than  our  previous  knowl- 
edge would  permit.  In  the  human  race,  this  condition  is 
characterized  by  the  following  symptoms  :  a  fixed  and  im- 
movable countenance,  a  peculiar  droopiQg  of  the  angles  of  the 
mouth,  a  collapsed  appearance  of  the  nostrils  during  inspira- 
tion, a  sinking  inward  of  the  cheeks  during  the  inspiratory 
effort,  and  a  protrusion  or  inflation  of  the  cheek  when  the  air 
is  expired.  The  tone  of  the  voice  becomes  of  the  most  dis- 
tinctly nasal  quality,  and  the  patient,  from  the  inability  to 
pronounce  the  labial  consonants,  is  almost  unable  to  make  the 
simplest  sentences  intelligible.  In  consequence  of  paralysis 
of  the  buccinator  muscles,  which  are  supplied  by  the  facial 
nerves,  the  act  of  mastication  becomes  embarrassed,  and  de- 
glutition is  greatly  interfered  with ;  hence  it  is  not  uncom- 
mon to  see  such  patients  use  the  finger  to  push  the  food  into 
the  grasp  of  the  isthmus  of  the  fauces,  so  as  to  swallow  the 
bolus.  When  the  head  is  inclined  forward,  the  saliva  runs 
from  the  mouth,  in  spite  of  all  efforts  to  prevent  it.  The  con- 
dition of  the  eyes,'  which  remain  wide  open  on  account  of  the 

'  As  quoted  by  Rosenthal. 

^  As  quoted  by  Hammond. 

^  In  both  the  unilateral  and  bilateral  forms  of  facial  paralysis,  the  patient  often  can 
avoid  the  irritation  of  dirt  and  the  intense  light  by  closing  the  eyelids  with  the  pressure 
of  the  finger,  or  by  a  strip  of  adhesive  plaster. 
15 


198 


THE  CRANIAL  NERVES, 


paralysis  of  the  orbicularis  palpebrarum  muscles,  affords  a 
most  important  point  in  the  discrimination  between  this  dis- 
ease and  the  paralysis  of  Duchenne.  So  marked  is  this  de- 
formity that  the  patient  can  not  wink,  and  thus  the  tears  are 
not  distributed  over  the  globe  of  the  eye,  to  wash  off  any  dust 
which  may  enter ;  while,  on  account  of  the  paralysis  of  the 
tensor  tarsi  muscle,  the  tears  are  not  drawn  into  the  lachry- 
mal sac,  and  therefore  tend  to  flow  over  the  cheek  and  create 
scalding. 

THE   AUDITORY,   OR  EIGHTH  NERVE. 

This  nerve  is  strictly  one  of  special  sense^  namely,  that  of 
hearing.  It  arises  from  a  gray  nucleus  in  the  floor  of  the 
fourth  ventricle  (where  its  fibers  form  the  so-called  '^linese 


Fig.  66. — A  diagram  of  the  auditory  nerve  and  its  branches. 

1,  audiiori/  nerve,  entering  the  meatus  auditorius  internus  ;  2,  communicating  filaments  to 
the  facial  nerve,  given  off  in  the  internal  auditory  canal ;  3,  filaments  given  off  to 
supply  the  cochlea  ;  4,  filaments  given  off  to  supply  the  posterior  semicircular  canal ; 
5,  filaments  given  off  to  supply  the  saccule  ;  6,  filaments  given  off  to  supply  the  utri- 
cle ;  7,  filaments  given  off  to  supply  the  external  semicircrdar  canal ;  8,  filaments  given 
off  to  supply  the  ampullce  of  the  superior  semicircular  canal. 

transversse  "  which  decussate  in  the  median  line),  and  also,  in 
part,  from  the  restiform  body  of  the  medulla  oblongata.  It 
is  claimed  by  Foville  ttiat  its  fibers  may  be  also  traced  to  the 
flocculus  and  the  gray  matter  of  the  cerebellum,  and,  from 
recent  statements  of  Lockhart  Clarke,  additional  fibers  may 
be  traced  from  the  auditory  nucleus,  which  pass  directly 
through  the  restiform  body  of  the  meduUa. 

The  course  of  the  nerve,  as  far  as  the  orifice  of  the  internal 


THE  AUDITORY,    OR  EIGHTH  NERVE.  199 

auditory  canal,  lies  parallel  with  tliat  of  the  facial  nerve,  since 
the  same  arachnoid  sheath  invests  them  both,  but,  before 
that  canal  is  reached,  a  filament  is  given  off  from  both 
these  nerves  to  form  an  intermediate  nerve,  called  the  "pars 
intermedia,"  or  the  ''nerve  of  Wrisberg."  This  intermediate 
portion  is  now  supposed  to  be  the  chief  source  of  origin  of  the 
chorda  tympani  nerve^  and  thus  to  be  connected  with  the 
special  sense  of  taste. 


Fig.  6*7. — Distribution  of  the  cochlear  nerve  in  the  spiral  lamina  of  the  cochlea  {the  cochlea 
is  from  the  right  side  and  is  seen  from  its  antero-inferior  part).     (Sappey.) 

1,  trunk  of  the  cochlear  nerve ;  2,  2,  2,  membranous  zone  of  the  spiral  lamina ;  3,  3,  3, 
terminal  expansion  of  the  cochlear  nerve,  exposed  in  its  whole  extent  by  the  removal 
of  the  superior  plate  of  the  lamina  spiralis ;  4,  orifice  of  communication  of  the  scala 
tympani  with  the  scala  vestibuli. 

The  color  of  the  auditory  nerve  filaments  is  grayish.  The 
filaments  differ  from  those  of  the  other  cerebro-spinal  nerves 
(excepting  those  of  special  sense)  in  having  a  softer  consist- 
ence. Some  of  the  later  researches  seem  to  show  that  the 
filaments  of  this  nerve  are  destitute  of  the  "white  substance 
of  Schwann,"  and  thus  resemble  those  of  the  olfactory  nerve, 
while  the  axis  cylinders  are  of  very  large  size  as  compared 
with  those  of  other  nerves.  It  is  also  claimed  that  small,  nu- 
cleated, ganglionic  enlargements  can  be  demonstrated  along 
the  course  of  these  fibers  of  the  trunk  of  the  nerve,  but  the 
minute  anatomy  of  the  auditory  nerve  is  yet  a  subject  for 
further  investigation. 

Within  the  internal    auditory  canal,   the    eighth   nerve 


200 


THE  CRAmAL  NERVES. 


divides  into  two  branches,  the  anterior  of  which  supplies  the 
cochlea,  while  the  posterior  branch  is  distributed  to  the  semi- 
circular canals  and  to  the  saccule  and  vestibule.  These  two 
main  branches  are  given  off  close  to  the  meatus  auditorius 
intemus. 

At  the  bottom  of  the  internal  auditory  canal,  the  three 
subdivisions  of  the  vestibular  nerve  pass  through  small  open- 


FiG.  68. — General  view  of  tlie  organ  of  hearing.     (Sappey.) 

1,  pinna ;  2,  cavity  of  the  concha,  on  the  walls  of  which  are  seen  the  orifices  of  a 
great  number  of  sebaceous  glands ;  5,  external  auditory  meatus ;  4,  angular  pro- 
jection formed  by  the  union  of  the  anterior  portion  of  the  concha  with  the  posterior 
wall  of  the  auditory  canal ;  5,  openings  of  the  ceruminous  glands,  the  most  internal 
of  which  form  a  curved  line,  which  corresponds  with  the  beginning  of  the  osseous 
portion  of  the  external  meatus  ;  6,  membrana  tympani  and  the  elastic  fibrous  mem- 
brane which  forms  its  border ;  7,  anterior  portion  of  the  incus ;  8,  malleus  ;  9,  han- 
dle of  the  malleus  applied  to  the  internal  surface  of  the  membrana  tympani,  which  it 
draws  inward  toward  the  projection  of  the  promontory  ;  10,  tensor  tympani  muscle, 
the  tendon  of  which  is  reflected  at  a  right  angle  to  become  attached  to  the  superior 
portion  of  the  handle  of  the  malleus;  11,  tympanic  cavity  ;  12,  Eustachian  tube,  the 
internal  or  pharyngeal  extremity  of  which  has  been  removed  by  a  section  perpen- 
dicular to  its  curve;  13,  superior  semicircular  canal ;  14,  posterior  semicircular  ca- 
nal; 16,  external  semicircular  canal ;  16,  cochlea ;  17,  internal  auditory  canal ;  18, 
facial  nerve  ;  19,  large  petrosal  branch,  given  off  from  the  panglioform  enlargement 
of  the  facial  and  passing  below  the  cochlea  to  go  to  its  distribution  ;  20,  vestibular 
branch  of  the  auditory  nerve  ;  21,  cochlear  branch  of  the  auditory  nerve. 

ings  in  a  cul-de-sac  situated  at  that  point,  and  are  distributed 
to  the  utricle,  the  saccule,  and  the  three  ampullae. 

The  cochlear  nerve,  which  is  the  other  main  branch  of  the 
auditory,  enters  the  base  of  the  modiolus^  and  its  filaments 


DISTRIBUTION  OF  AUDITORY  NERVE.  201 

subsequently  escape  from  the  central  canal  of  the  modiolus 
through  minute  canals^  which  enable  them  to  reach  their 
point  of  distribution  in  the  internal  portion  of  the  cochlea. 
The  terminal  filaments  of  this  nerve  are  now  believed  to  be 
connected  with  the  spindle-shaped  cells  of  the  organ  of  CortL 

It  is  impossible,  within  the  compass  of  this  lecture,  to  en- 
ter into  the  minute  anatomy  of  the  ear  with  sufficient  detail 
to  enable  you  to  properly  appreciate  the  mechanism  by  which 
the  waves  of  sounds,  produced  from  without,  are  transmitted 
to  the  membrana  tympani,  and  subsequently  to  the  cochlea, 
where  they  are  perceived  by  the  auditory  nerve  filaments.  To 
properly  appreciate  the  difficulties  which  arise  in  determining 
the  exact  method  by  which  the  human  ear  is  enabled  to  de- 
termine not  only  the  intensity  of  the  sound  perceived,  but 
also  its  pitchy  quality^  and  musical  properties^  not  only 
would  the  anatomy  have  to  be  given  in  detail,  but  many  of 
the  laws  of  physics  discussed.  The  following  general  state- 
ments, however,  may  assist  you  in  studying  this  complicated 
subject,  and  afford  an  explanation  of  some  of  those  symp- 
toms of  disease  which  are  referred  to  the  ear. 

The  diagram  shown  you  on  the  blackboard '  is  designed  to 
assist  you  to  grasp  some  of  the  principal  points  in  the  ana- 
tomical construction  of  the  ear,  which  are  necessary  for  the 
clear  comprehension  of  the  physiology  of  audition.  It  can  be 
perceived  that  the  external  auditory  canal  and  its  accessory 
portion  which  we  call  the  ear  or  auricle  (which  is  placed 
on  the  exterior  of  the  skull  for  the  purpose  of  deflecting  the 
waves  of  sound  into  that  canal)  lie  external  to  the  membrana 
tympani  ;  and,  for  that  reason,  all  of  these  parts,  viz.,  the 
cartilages  of  the  pinna,  its  ligaments,  the  bony  canal  leading 
to  the  membrana  tympani,  and  its  cutaneous  lining,  are  in- 
cluded under  the  general  term  "  the  external  ear^''  in  contrast 
to  the  chambers  which  lie  deeply  within  the  temporal  bone, 
called  the  middle  ear,  or  ^Hhe  cavity  of  the  tympanum,''  and 
the  internal  ear,  or  the  "labyrinth.''' 

The  middle  ear,  or  "  tympanum,"  lies  between  the  mem- 

'  See  diagram  further  on  in  the  chapter. 


202  THE  GRANIAL  NERVES. 

brana  tympani  and  the  internal  ear,  or  "labyrintli,"  and  is 
contained  within  the  petrous  portion  of  the  temporal  bone. 
It  communicates  with  the  pharynx^  by  means  of  the  Eusta- 


Fio.  69. — A  diagram  to  illvMraie  the  mechanism  of  the  act  of  hearing. 

A,  the  auditorg  canal  (the  arrow  showing  the  waves  of  sound  entering) ;  B,  the  cavity  of 
the  middle  ear,  or  "  tympanum  ") ;  C,  the  utricle,  communicating  with  the  semicircu- 
lar canals ;  D,  the  saccule,  communicating  with  the  scala  vestihdi  of  the  cavity  of  the 
cochlea ;  E,  the  Eustachian  tube,  allowing  of  the  entrance  of  air  into  the  middle  ear 
from  the  pharynx;  1,  the  memhrana  tympani,  which  first  receives  the  vibrations  of 
the  waves  of  sound  ;  2,  the  chain  of  bones,  which  transmit  these  vibrations  to  the  mem- 
brane covering  the  fenestra  ovalis  (annular  ligament  of  the  stapes)  ;  3,  the  membrane, 
covering  ihe  fenestra  ovalis  (annular  ligament  of  the  stapes) ;  4,  the  foramen  rotun- 
dum,  where  the  waves  of  sound  return  to  the  cavity  of  the  middle  ear  and  are  lost 
(membrana  tympani  secundaria) ;  5,  the  ampullae  of  the  semicircular  canals ;  6,  the 
semicircular  canals  ;  7,  the  "  scala  vestibtdi "  of  the  cochlea  ;  8,  the  cupola,  at  the  apex 
of  the  cochlea,  where  the  scala  vestibuli  and  the  scala  tympani  of  the  cochlea  join 
each  other;  9,  the  "  scala  tympani,''^  leading  downward  from  the  cupola  of  the  cochlea 
to  the  foramen  rotundum ;  10,  irUemal  auditory  canal,  where  the  auditory  nerve 
enters. 

chian  tube,  and  is  thus  enabled  to  afford  free  access  to  the 
air  of  the  external  world,  and  insure  the  same  density  of  at- 
mosphere on  both  sides  of  the  membrana  tympani.  It  is 
this  anatomical  arrangement  that  causes  gunners  to  hold  the 
mouth  wide  open  when  exploding  large  pieces  of  ordnance,  to 
avoid  a  rupture  of  the  membrana  tympani,  since  the  waves  of 
sound  can  thus  enter  the  Eustachian  tube  at  the  same  time 
that  they  pass  down  the  external  auditory  canal,  and  the 
membrana  tympani  should,  theoretically,  be  made  to  stand 


TEE  MIDDLE  EAR. 


203 


motionless,  if  the  EustacMan  tube  were  wide  open,  since  the 
waves  of  sound  upon  each  side  of  the  membrane  would  neu- 
tralize each  other/  In  the  cavity  of  the  middle  ear,  a  cTiain 
of  small  hones  is  so  arranged  as  to  afford  a  source  of  trans- 
mission of  the  impulses  of  sound  from  the  membrana  tym- 
pani  to  the  fenestra  ovalis,'  which  is  closed  by  the  stapes' 


Fig.  70. —  Ossicles  of  the  tympanum  of  the  right  side,  magnified  4  diameters.     (Arnold.) 

A,  malleus ;  1,  its  head ;  2,  the  handle  ;  3,  long,  or  slender  process  ;  4,  short  process  ;  B, 
incus  ;  1,  its  body ;  2,  the  long  process  with  the  orbicular  process  ;  3,  short,  or  pos- 
terior process  ;  4,  articular  surface  receiving  the  head  of  the  malleus  ;  C,  stapes  ;  1, 
head ;  2,  posterior  crus  ;  3,  anterior  crus ;  4,  base  ;  C*  base  of  the  stapes  ;  D,  the 
three  bones  in  their  natural  connection  as  seen  from  the  outside ;  a,  malleus ;  6, 
incus ;  c,  stapes. 

and  its  annular  ligament.  This  chain  of  bones  is  suspend- 
ed by  a  ligament  attached  to  the  roof  of  the  middle  ear,  and 
the  separate  bones  are  connected  together  by  joints*  lined 
with  synovial  membranes,  so  that  the  slightest  movement  is 
readily  carried  from  one  to  the  other.  Muscles  are  also  at- 
tached to  these  bones,  for  the  object  of  bringing  the  mem- 

'  Valsalva's  method,  "  which  consists  of  making  a  powerful  expiration,  with  the  mouth 
and  nostrils  closed,"  is  also  used  if  the  ear  be  stopped  with  cotton  at  the  same  time. 

2  A  doctrine  first  suggested  in  1851  by  Edward  Weber,  and  subsequently  verified  by 
experiments  in  1868  by  Politzer. 

^  One  of  the  small  bones  of  the  middle  ear. 

*  Helmholtz  first  described  the  exact  nature  of  the  joint  between  the  malleus  and  the 
incus.  He  compared  it  to  "  a  joint  used  in  certain  watch-keys,  where  the  handle  can  not 
be  turned  in  one  direction  without  carrying  the  steel  shell  with  it,  while  in  the  other  direc- 
tion it  meets  with  only  a  slight  resistance."  This  device  assists  to  convert  the  bones  into 
a  state  of  resistance,  resembling  that  of  a  solid  piece  of  bone,  when  muscular  action  locks 
this  joint  firmly. 


204 


THE  CRANIAL  NERVES. 


brana  tympani  and  the  bones  themselves  into  the  best  possi- 
ble condition  for  the  accurate  appreciation  of  sound  im- 
pulses.' The  cavity  of  the  middle  ear  is  in  communication 
with  the  cells  in  the  mastoid  portion  of  the  temporal  bone, 
and  some  additional  effect  may  be  thus  produced  upon  the 
vibrations  of  the  air  within  the  middle  ear.' 


Fig.  71. —  TJie  left  bony  labyrinth  of  a  neio-born  child,  foytoard  and  outward  view.     Modi- 
fied from  a  photograph.     (Riidinger.) 

1,  the  wide  canal,  the  beginning  of  the  spiral  canal  of  the  cochlea ;  2,  the  fenestra  ro- 
tunda ;  3,  the  second  turn  of  the  cochlea ;  4,  the  final  half  turn  of  the  cochlea ; 
5,  the  border  of  the  bony  wall  of  the  vestibule,  situated  between  the  cochlea  and 
the  semicircular  canals ;  6,  the  superior,  or  sagittal  semicircular  canal ;  7,  the  portion 
of  the  superior  semicircular  canal  bent  outward ;  8,  the  posterior,  or  transverse 
semicircular  canal ;  9,  the  portion  of  the  posterior  connected  with  the  superior  serai- 
circular  canal ;  10,  point  of  Junction  of  the  superior  and  the  posterior  semicircular 
canal;  11,  the  ampulla  ossea  externa;  12,  the  horizontal,  or  external  semicircular 
canal. 

The  internal  ear,  or  '' labyrinth,^ ^  lies  within  the  petrous 
portion  of  the  temporal  bone,  and  internal  to  the  tympanum. 
It  consists  of  a  series  of  chambers,  hollowed  out  within  the 
bone,  called  the  vestibule^  the  cochlea^  and  the  semicircular 

'  The  tensor  tympani  muscle,  on  account  of  a  peculiar  arrangement  of  the  joint  be- 
tween the  malleus  and  the  incus,  renders  all  the  articulations  firm,  tightens  the  little  liga- 
tures, and  presses  the  stapes  against  the  fenestra  ovalis,  thus  bringing  it  in  contact  with 
the  fluids  of  the  vestibule.     Sec  foot-note  on  page  203. 

^  For  the  surgical  application  of  this  arrangement,  see  article  on  the  bones  of  the 
head,  by  the  author,  "  New  York  Medical  Record,"  October  16,  1880. 


THE  INTERNAL  EAR.  205 

canals,  within  each  of  which  a  membranous  tube  is  sus- 
pended between  two  liquids,  one  within  the  tube,  the  "en- 
dolymph,"  and  one  between  the  tube  and  the  bony  walls,  the 
' '  perilymph. "     This  membranous  portion  is  called  the  ' '  mem- 


Fig.  72. — Diagram,  of  the  lahyrinth^  vestibule^  and  semicircular  canals.     From  a  photo- 
graphy and  somewhat  reduced.     (Riidinger.) 

Upper  figure:  1,  utricle;  2,  saccule;  3,  5,  membranous  cochlea;  4,  canalis  reuniens;  6, 
semicircular  canals. 

Lower  figure:  1,  utricle;  2,  saccule ;  3,  4,  6,  ampullae;  5,  7,  8,  9,  semicircular  canals; 
10,  auditory  nerve  (partly  diagrammatic);  11,  12,  13,  14,  15,  distribution  of  the 
branches  of  the  nerve  to  the  vestibule  and  the  semicircular  canals ;  16,  ganglioform 
enlargement. 

hranous  labyrinth^'^^  and  is  an  exact  reproduction  of  the 
bony  labyrinth,  except  that  it  is  smaller  in  point  of  size,  so  as 
to  admit  the  presence  of  fluid  between  it  and  the  bone.  It 
serves  as  a  support  for  the  terminal  filaments  of  the  auditory 
nerve,  which,  by  being  suspended  between  two  fluids,  are  en- 


206  THE  CRANIAL  NERVES. 

abled  not  only  to  perceive  tlie  slightest  vibrations  of  the 
fluids/  but  are  also  thus  protected  from  the  possibility  of  in- 
jury, which  would  be  great  were  they  placed  in  contact  with 
the  bone.  The  membranous  labyrinth  which  fills  the  cavity 
of  the  vestibule  is  divided  into  two  portions,  called  the  saccule 
and  the  utricle;  the  former  of  which  communicates  directly 
with  the  cochlea,  while  the  latter  communicates  with  the 
semicircular  canals,  as  can  be  seen  in  the  diagram. 

The  cochlea  is  essentially  that  part  of  the  internal  ear 
which  is  enabled  to  appreciate  most  of  the  important  elements 
of  sound,  viz.,  its  note  and  quality ^    It  consists  of  an  exca- 


FiG.  73. — A  transverse  section  of  the  spiral  canal  of  the  cochlea  {diagrammatic).^ 

S.  v.,  the  scala  vestihuli  ;  S.  M.,  the  scala  media  ;  S.  T.,  the  scala  tympani ;  1,  mem- 
brane of  Reissner ;  2,  "  organ  of  Corli^''  covered  by  the  "  memhrana  iectoria,''^  or 
"  membrane  of  Corti "  /  3,  membrana  basilaris  ;  4,  ligamentum  spiralis^  extending 
the  whole  length  of  the  spiral  canal  of  the  cochlea ;  5,  upper  layer  of  the  lamina 
spiralis  ossea  ;  6,  lower  layer  of  the  lamina  spiralis  ossea  ;  7,  a  nerve  filament  es- 
caping from  the  central  canal  of  the  modiolus^  and  going  to  the  organ  of  Corti  ;  8,  a 
ganglion  attached  to  the  nerve  filament,  called  the  "  ganglion  spirale." 

vation  in  the  temporal  bone  which  resembles,  in  its  construc- 
tion, the  shell  of  a  snail,  having  a  central  pillar,  the  Tnodio- 
lus,  which  runs  from  its  base  to  its  apex,  and  a  spiral  canal^ 

'  It  is  a  well-recognized  law  of  physics  that  the  fluids  transmit  vibrations  in  every 
direction  with  equal  force,  and,  therefore,  no  better  medium  could  possibly  be  had  for 
the  auditory  nerve  filaments  to  be  in  contact  with. 

^  Complete  destruction  of  the  cochlea  probably  causes  total  deafness,  while  destruction 
of  the  semicircular  canals  does  not  seem  to  have  any  marked  effect  upon  the  ability  to 
appreciate  sound.  • 

*  From  the  "  Essentials  of  Anatomy  "  (Darling  and  Ranney),  New  York,  1880. 


I 


C0N8TEUGTI0N  OF  THE  COCHLEA.  207 

running  around  this  central  portion  for  two  and  a  half  com- 
plete turns.  The  spiral  canal  of  the  cochlea  is  divided  into 
three  portions  called  the  scala  mstihuU,  scala  tympani,  and 
the  scala  medial    The  first  communicates,  at  its  lower  part 


Fig.  74. —  Vertical  section  of  the  organ  of  Corti  of  the  dog,  magnified  800  diameters. 

(Waldeyer.) 

a-6,  homogeneous  layer  of  the  basilar  membrane ;  v,  tympanic  layer,  with  nuclei,  granu- 
lar cell  protoplasm,  and  connective  tissue  ;  ai,  tympanic  lip  of  the  crista  spiralis  ;  c, 
thickened  portion  of  the  basilar  membrane  ;  d,  spiral  vessel ;  e,  blood-vessel ;  /,  h, 
bundle  of  nerves ;  g,  epithelium ;  i,  inner  hair  cell,  with  its  basilar  process,  Jc  ;  /, 
head-plate  of  the  inner  pillar ;  m,  union  of  the  two  pillars ;  «,  base  of  the  inner 
pillar  ;  o,  base  of  the  outer  pillar  ;  /),  ^,  r,  outer  hair  cells,  with  traces  of  the  cilia  ; 
t,  bases  of  two  other  hair  cells  ;  z,  Hensen's  prop  cell ;  l-h,  lamina  reticularis  ;  w, 
nerve  fiber  passing  to  the  first  hair  cell,  p. 

with  the  vestibule  ;  hence  its  name  ;  the  second  terminates  in 
the  middle  ear,  and  hence  its  name ;  while  the  third  is,  in 

^  The  experiments  of  Laborde  (Des  fonctions  du  limagon,  "  Trib.  Med.,"  Septembre 
12,  1880)  to  determine  the  function  of  the  cochlea  were  made  upon  the  Guinea-pig,  an 
animal  in  whom  the  organ  is  particularly  accessible.  The  following  facts  were  considered 
by  him  as -fully  proven  :  1,  Destruction  of  the  cochlea  had  no  effect  in  the  production  of 
vertigo  or  disturbances  of  coordination  ;  2,  destruction  of  the  cochlea  produced  complete 
deafness,  which,  however,  did  not  appear  until  several  days  after  the  operation. 

He  concludes,  from  these  facts :  1,  That  the  auditory  nerve  contains  both  motor  and 
sensory  fibers,  the  former  being  distributed  to  the  semicircular  canals,  the  latter  to  the 
saccule,  utricle,  and  cochlea  ;  2,  that  the  cochlea  is  not  the  only  organ  for  the  appreciation 
of  sound,  since  the  utricle  and  saccule  participate,  to  some  unknown  extent,  in  that  func- 
tion ;  3,  that  the  deafness  which  occurs  after  excision  of  the  cochlea  alone  is  probably 
due  to  an  extension  of  inflammation  to  the  utricle  and  saccule,  or  to  the  formation  of  a 
rigid  cicatrix,  which  prevents  the  transmission  of  an  auditory  impulse  to  those  parts. 
While  these  facts  need  subsequent  confirmation  (since  the  experiments  are  by  no  means 
conclusive),  they  are  worthy  of  due  consideration  in  the  discussion  of  this  complicated 
and  imperfectly  understood  organ. 


208 


TEE  CRANIAL  NERVES. 


reality,  but  a  space  partitioned  off  from  the  scala  vestibuli 
for  the  protection  of  the  true  organ  of  hearing,  "the  organ 
of  Corti."  The  preceding  diagram  (Fig.  73)  will  help  to  make 
this  plain  to  you. 

This  figure  represents,  in  a  diagrammatic  way,  the  appear- 
ance of  a  longitudinal  section  of  the  spiral  cord  in  the  cochlea, 
in  any  portion  of  its  two  and  a  half  turns  around  the  modio- 
lus. It  will  be  perceived  at  a  glance  that  the  canal  is  divided 
into  an  upper  {s.  v.)  and  a  lower  {s.  t.)  portion,  partly  by  bone 
(5  and  6)  and  partly  by  membrane  (3).  It  will  also  be  readily 
seen  that  a  portion  of  the  scala  vestibuli  is  divided  off  by  the 
membrane  of  Reissner^  and  that  thus  a  separate  cavity  is 
formed  throughout  the  whole  length  of  the  spiral  canal,  called 
the  ''scala  media."  Within  this  last-named  cavity  will  be 
noticed  a  body  covered  with  hair-like  processes,  "the  organ 
of  Corti^^''  which  rests  upon  the  membrane  forming  the  floor 
of  the  scala  media,  and  called  for  that  reason  the  ''basilar 


Fig.  75. — TJie  two  pillars  of  the  organ  of  Corti.     (Sappey.) 

A,  external  pillar  of  the  organ  of  Corti :  1,  body,  or  middle  portion  ;  2,  posterior  extrem- 

ity, or  base  ;  3,  cell  on  its  internal  side  ;  4,  anterior  extremity ;  5,  convex  surface  by 
which  it  is  joined  to  the  internal  pillar ;  6,  prolongation  of  this  extremity. 

B,  internal  pillar  of  the  organ  of  Corti :   1,  laody,  or  middle  portion;  2,  posterior  extrem- 

ity ;  3,  cell  on  its  external  side  ;  4,  anterior  extremity ;  5,  concave  surface  by  which 
it  is  joined  to  the  external  pillar ;  6,  prolongation,  lying  above  the  corresponding 
prolongation  of  the  external  pillar. 

C,  the  two  pillars  of  the  organ  of  Corti,  united  by  their  anterior  extremity,  and  forming 

an  arcade,  the  concavity  of  which,  looks  outward  :  1,  1,  body,  or  middle  portion  of 
the  pillars  ;  2,  2,  posterior  extremities  ;  3,  3,  cells  attached  to  the  posterior  extrem- 
ities ;  4,  4,  anterior  extremities  joined  together ;  5,  terminal  prolongation  of  this 
extremity. 


membrane.''^  There  is,  furthermore,  shown  in  this  figure  the 
means  by  which  the  terminal  filaments  of  the  cochlear  nerve 
(one  of  the  branches  of  the  auditory  nerve)  escape  from  the 
central  canal  of  the  modiolus  and  reach  the  scala  media. 


THE  ORGAN  OF  CORTL 

Such  a  figure  will  greatly  assist  you  to  properly  appreciate 
the  discussion  of  the  function  of  each  of  these  various  parts, 
and  also  enable  you  to  grasp  the  principal  points  in  the 
physiology  of  the  act  of  hearing,  which  are  to  be  con- 
sidered. 

The  organ  of  Corti  may  be  compared  to  a  harp,  since  its 
rods  are  of  dijfferent  lengths.  It  is  a  continuous  structure  for 
the  entire  course  of  the  spiral  canal  of  the  cochlea.  Helm- 
holtz  has  advanced  the  theory '  that  the  several  thousand 
strings  of  this  organ  admit  of  the  appreciation  of  all  varieties 
of  musical  tone,  since  each  note  or  chord  creates  a  vibration 


Fig.  76, — Distribution  of  the  cochlear  nerve  in  the  spiral  lamina  of  the  cochlea  {the  cochlea 
is  from  tJie  right  side  and  is  seen  from  its  antero-inferior  part).     (Sappey.) 

1,  trunk  of  the  cochlear  nerve;  2,  2,  2,  membranous  zone  of  the  spiral  lamina;  3,  3,  3, 
terminal  expansion  of  the  cochlear  nerve,  exposed  in  its  whole  extent  by  the  removal 
of  the  superior  plate  of  the  lamina  spiralis ;  4,  orifice  of  communication  of  the  scala 
tympani  with  the  scala  vestibuli. 

in  those  strings  only  which  are  necessary  to  reproduce  it,  in 
the  same  way  as  a  piano,  when  a  note  is  sounded,  will  create 
a  vibration  in  the  same  string  of  an  adjoining  instrument. 
Hensen,  however,  claims  that  the  basilar  membrane  is  com- 
posed of  elastic  fibers  of  varying  lengths^''  and  that  these 
separate  fibers  are  thrown  into  vibration  by  sounds  carried  to 
the  cochlea,  which,  in  turn,  transmit  their  vibration  to  the 

'  This  theory  is  opposed  by  the  facts  that  the  rods  of  Corti  are  not  elastic,  and  they 
are  absent  in  birds,  who  can  unquestionably  perceive  sound. 
-  By  some  authors  this  theory  is  attributed  to  Helmholtz. 


210  THE  CRANIAL  NERVES. 

organ  of  Corti  lying  upon  them,  and  thus  inform  the  auditory- 
nerve  filaments  of  the  effect  of  each  individual  sound/ 

In  the  act  of  hearing,  the  vibrations  produced  within  the 
membrana  tympani  by  the  waves  of  sound  are  transmitted 
across  the  cavity  of  the  middle  ear,  to  a  membrane  covering 
an  opening  nearly  opposite  the  external  drum,  called  the 
fenestra  ovalis^  by  means  of  a  chain  of  small  bones  within 
the  cavity  of  the  middle  ear,  and,  by  means  of  secondary 
vibrations  thus  produced  within  this  latter  membrane,  the 
impulse  is  transmitted  to  the  fluids  of  the  mstibule.  The 
vibrations  now  travel  along  the  fluids  of  the  scala  vestibuli  of 
the  cochlea  and  of  the  semicircular  canals,  thus  passing  in 
two  different .  directions.  In  the  semicircular  canals,  accord- 
ing to  some  observers,  the  direction  from  which  the  sound 
springs  is  perceived,'  while  the  vibrations  carried  along 
the  scala  media '  in  the  cochlea  are  transmitted  to  the  fila- 
ments of  the  auditory  nerve  in  the  "  organ  of  Corti,"  proba- 
bly by  means  of  vibrations  of  the  membrana  hasilaris,  thus 
affording  the  appreciation  of  the  note  and  the  quality  of 
the  sound  perceived.  After  reaching  the  apex  of  the  coch- 
lea, the  vibrations  are  transmitted  from  the  scala  vestibuli 
downward  along  the  course  of  the  scala  tympani  till  they 
reach  the  ''membrana  tympani  secundaria,"  which  covers 
ihe  fenestra  rotunda^^  whQTQ  they  are  lost,*  being  no  longer 

^  The  membrana  tedoria,  or  "  membrane  of  Corti,"  probably  acts  as  a  damper,  to 
arrest  the  vibrations  excited  within  the  scala  media,  as  its  situation  suggests  no  other  pos- 
sible function. 

'  The  function  of  the  semicircular  canals  is  yet  a  matter  of  doubt,  and  is  now  receiv- 
ing the  attention  of  experimental  physiologists.  They  are  supposed  by  some  authors  to 
relieve  excessive  pressure  within  the  labyrinth  when  the  stapes  is  driven  too  forcibly  in- 
ward ;  and,  by  others,  to  secrete  the  fluid  of  the  labyrinth  ;  while  by  some  they  are  consid- 
ered to  be  the  external  organs  of  coordination  of  muscular  movement. 

•3  The  saccule  communicates  with  the  scala  media  by  means  of  a  small  canal  (shown 
in  Fig.  72),  called  the  "  canalis  reuniens." 

*  An  opening  in  the  inner  wall  of  the  cavity  of  the  middle  ear. 

^  According  to  some  authorities,  the  vibrations  in  the  membrana  tympani  secundaria 
are  created,  simultaneously  with  those  at  the  fenestra  ovalis,  by  the  vibrations  of  the 
air  in  the  middle  ear  created  by  the  movements  of  the  external  drum  membrane,  and 
an  impulse  thus  travels  simultaneously  along  the  scala  tympani  and  the  scala  vestibuli, 
both  goiwj  in  the  same  direction,  to  meet  each  other  at  the  cupola.  They  consider  the  second 
drum,  at  the  foramen  rotundum,  as  a  proof  of  this  function,  but  it  must  be  apparent  to  any 
one  that  all  the  openings  of  the  labyrinth  into  the  middle  ear  must  be  closed  in  some  way 


PHYSIOLOGY  OF  AUDITION.  211 

transmitted,  on  account  of  the  absence  of  any  conducting 
medium. 

The  free  entrance  of  air  to  the  cavity  of  the  tympanum, 
or  the  middle  ear,  affords  an  equal  density  of  air  upon  either 
side  of  the  membrana  tympanic  and  thus  insures  a  vibration 
of  that  membrane  in  absolute  unison  with  the  vibrations  of 
the  sound  which  it  is  called  upon  to  record,  as  the  waves  pass 
down  the  external  auditory  canal. 

The  function  of  the  organ  of  Cort%  of  the  membrana  hasi- 
laris^  or  of  the  otoliths^  can  not  be  stated  with  any  degree  of 
certainty,  since  new  discoveries  are  constantly  being  made, 
although  some  theories  of  their  functions  have  been  already 
given. 

The  minute  construction  of  the  scala  media  and  its  con- 
tained organs  can  be  found  by  reference  to  more  extensive 
treatises. 

CLINICAL    POIN^TS    OF    INTEREST    DEPEN^DEN^T    UPON    THE    AUDITORY 

NERVE. 

In  attacks  of  auditory  vertigo,  or  Meniere's  disease,  there 
is  much  more  than  ordinary  giddiness.    The  patient  will  often 

to  prevent  the  escape  of  the  perilymph.  While  it  is  difficult  to  positively  decide  this  point, 
I  am  personally  inclined  to  regard  the  foramen  rotundum  as  the  seat  of  termination  of 
wave  sounds,  rather  than  a  means  of  transmim.on  of  impulses  to  the  fluids  of  the  cochlea. 
Dr.  A.  H.  Buck,  in  a  late  treatise  on  the  "  Diagnosis  and  Treatment  of  Ear  Diseases," 
again  advocates  theories  long  maintained  by  him  as  to  the  physiology  of  audition,  which 
may  be  thus  given :  The  impulse  of  the  stapes,  at  the  fenestra  ovalis,  is  carried  by  means 
of  the  perilymph  directly  into  the  scala  vestibuli.  This  causes  compression  of  the  fluid  in 
the  scala  media,  which,  in  turn,  causes  pressure  upon  and  movement  of  the  elastic  "  mem- 
brana basilaris."  The  pressure  is  thus  transmitted,  for  a  second  time,  to  the  fluid  in  the 
scala  tympani,  and,  as  fluids  are  incompressible,  the  membrana  tympani  secundaria,  which 
closes  the  foramen  rotundum,  is  forced  into  the  cavity  of  the  middle  ear  until  the  force 
is  expended,  when  it  returns  to  its  normal  condition.  It  will  be  thus  perceived  that  he 
discards  the  saccule  and  the  canalis  reuniens  as  a  channel  for  the  passage  of  the  acoustic 
wave.  He  also  questions  the  existence  of  any  communication,  at  the  cupola,  between  the 
scala  vestibuli  and  the  scala  tympani.  While  his  theory  seems  ingenious,  and  perhaps 
more  in  accordance  with  fact  than  the  older  views,  and  is  well  illustrated  by  diagrams 
and  supported  by  some  carefully  conducted  experiments,  still  it  can  not,  as  yet,  be  said 
to  be  positively  confirmed.  His  view  as  to  the  absurdity  of  the  membrana  tympani  se- 
cundaria being  a  transmitter  of  sound  waves  to  the  cochlea  agrees  with  my  own,  as  advo- 
cated above.  He  seems  also  to  favor  the  theory  that  the  basilar  membrane  is  the  true 
vibrating  medium,  which  carries  to  the  auditory  nerve  the  appreciation  of  the  note 
sounded,  rather  than  the  "  organ  of  Corti." 


212 


THE  CRANIAL  NERVES. 


tell  you  that,  when  the  attack  commenced,  everything  began 
to  whirl,  or  possibly  appeared  to  be  moving  toward  one  side  ; 
that  his  gait  became  unsteady,  and,  if  walking  was  possible, 
that  he  reeled  and  staggered  ;  while,  in  some  severe  cases,  the 
patient  feels  unsafe  even  when  lying  upon  a  bed  or  sofa,  and 
may  be  obliged  to  grasp  the  sides  of  the  couch  to  protect  him- 


FiG.  77. — Right  memhrana  tympanic  seen  from  within.     From  a  photography  and  somewhat 

reduced.     (Riidinger.) 

1,  head  of  the  malleus,  divided ;  2,  neck  of  the  malleus  ;  3,  handle  of  the  malleus,  with 
the  tendon  of  the  tensor  tyrapani  muscle  ;  4,  divided  tendon  of  the  tensor  tympani ; 
6,  6,  portion  of  the  malleus  between  the  layers  of  the  membrana  tympani ;  7,  outer 
(radiating)  and  inner  (circular)  fibers  of  the  membrana  tympani ;  8,  fibrous  ring  of 
the  membrana  tympani;  9,  14,  15,  dentated  fibers,  discovered  by  Gruber;  10,  poste- 
rior pocket;  11,  connection  of  the  posterior  pocket  with  the  malleus;  12,  anterior 
pocket;  13,  chorda  tympani  nerve. 

self  from  a  sensation  of  falling.  In  many  cases,  these  symp- 
toms are  markedly  intensified  by  movement  of  the  liead^  and, 
in  some  instances,  such  movements  often  tend  to  bring  about 
an  attack.'    The  patient  is  usually  pale  and  haggard,  some- 

'  Buzzard,  "Lancet,"  March  4,  1876. 


MEmERE'S  DISEASE.  213 

times  perspires  freely,  and  often  vomits/  while  ^am  within 
the  head  is  a  symptom  which  not  infrequently  accompanies 
such  an  attack.  The  extent  to  which  this  type  of  vertigo 
may  be  manifested  varies  from  an  attack  of  but  momentary 
duration,  where  the  patient  can  retain  his  feet,  to  those  severe 
forms  of  the  disease  where  the  attack  is  accompanied  by  a 
loss  of  consciousness,  which  may  remain  for  some  hours,  and 
resemble  the  condition  of  epileptic  vertigo. 

There  seems  to  be  little  doubt  that,  in  these  cases,  the  at- 
tack is  always  preceded  or  followed  by  some  abnormal  con- 
dition of  the  ear,  and  that  this  diseased  condition  was  the 
starting  point  of  the  vertigo."  Sometimes  the  patient  has 
long  been  deaf  in  one  ear,  or  a  condition  of  deafness  may 
follow  the  first  attack  of  vertigo ;  again,  the  approach  of  an 
attack  of  vertigo  may  be  told  by  the  occurrence  of  noises 
within  the  ear  of  one  side,  while,  in  some  cases,  there  exists 
a  constant  noise  within  the  ear,  which  increases  as  the  attack 
of  vertigo  is  imminent. 

It  is  often  extremely  difficult  to  persuade  a  patient,  suffer- 
ing from  this  affection,  that  the  attack  is  not  dependent  upon 
a  disordered  state  of  the  digestive  apparatus,  and  especially  is 
this  the  case  when  the  ear  trouble  is  of  old  standing,  or  when 
the  patient  is  unconscious  of  any  defect  in  his  hearing,  which 
is  by  no  means  an  unusual  occurrence.  Such  patients  are 
better  satisfied  if  the  attack  be  attributed  to  the  liver,  dys- 
pepsia, or  nervousness.  I  quote  the  following  sentence  from 
Hughlings- Jackson  ^  as  evidence  that  this  difficulty  is  met 
with  even  among  the  most  enlightened  of  the  community. 
He  says  :  "  Even  medical  men,  who  have  aural  disease,  often 
totally  reject  the  proffered  explanation  of  their  attacks  of 
vertigo  ;   many  of  them  ascribe  their  ailment  to  digestive 

^  Ferrier,  "  Vomiting  in  connection  with  cerebral  disease,"  "  Brain,"  July,  1870. 

^  The  occurrence  of  vertigo  and  interference  with  coordination  is  not  alone  produced 
by  local  disease  of  the  ear,  even  when  associated  with  impairment  of  hearing.  It  may 
indicate  disease  of  the  cerebellum  or  of  the  medulla  oblongata,  which  creates  irritation  of 
or  some  interference  with  the  auditory  nucleus.  For  the  clinical  facts  pertaining  to  this 
symptom,  the  reader  is  referred  to  pages  63  and  64  of  this  volume. 

3  Hughlings-Jackson,  "Lancet,"  March  11,  1876  ;  same  author,  "Lancet,"  March  11, 
1876;  Gowers,  "Lancet,"  March,  October,  1880. 
16 


214  THE  CRANIAL  NERVES. 

troubles.     A  medical  man  had  deafness  in  his  left  ear,  with, 
occasional  slight  vertigo.     One  day,  while  walking  in  his  gar- 


Fio.  78. — Section  of  the  first  turn  of  the  spiral  canal  of  a  cat  newli^-born. — Section  of  the. 
cochlea  of  a  human  foetus  at  the  fourth  momth.  From  a  "photography  and  somewhat 
1-educed/  (Riidinger.) 

Upper  figure:  1,  2,  6,  lamina  spiralis;  2,  lower  plate-,  3,  4,  5,  5,  nervus  cochlearis;  7, 
membrane  of  Reissner  ;  8,  membrana  tectoria  :  9,  epithelium  ;  10, 11,  pillars  of  Corti ; 
12,  inner  hair  cells;  13,  outer  hair  cells;  14,  16,  membrana  basilaris;  15,  epithe- 
lium in  the  sulcus  spiralis ;  17,  18,  19,  ligamentum  spirale ;  20,  spiral  canal  below 
the  membrana  basilaris. 

Lower  figure  :  S  T,  S  T,  5,  6,  7,  7,  8,  8,  scala  tympani ;  S  V,  S  V,  9,  9,  scala  vestibuli ;  1, 
base  of  the  cochlea  ;  2,  apex  ;  8,  4,  central  column  ;  10,  10,  10,  10,  ductus  cochlearis; 
11,  branches  of  the  nervus  cochlearis ;  12, 12, 12,  spiral  ganglion ;  13,  14,  limbus  lami- 
nae spiralis ;  15,  membrane  of  Ileissner  ;  16,  epithelium  ;  17,  outer  hair  cells  ;  18,  epi- 
thelium of  the  membrana  basilaris ;  19,  nervous  filaments ;  20,  union  of  the  membrana 
basilaris  with  the  ligamentum  spirale  ;  21,  epithelium  of  the  peripheral  wall  of  the 
ductus  cochlearis  ;  22,  23,  membrana  tectoria  ;  24,  spiral  canal  below  the  membrana 
basilaris. 


FUNCTION  OF  SEMICIRCULAR   CANALS.  215 

den,  he  had  a  pain  in  his  head,  was  very  giddy,  fell  in  the 
shrubs,  and  vomited.  This  was  plainly  ear  vertigo,  as  he 
himself  knew.  Bnt  he  had  the  following  diagnoses  made  of 
his  case  by  other  medical  men :  1,  nothing  ;  2,  nervousness ; 
3,  deranged  stomach." 

That  some  persons  who  are  deaf  in  one  ear  are  absolutely 
unconscious  of  it  is  too  often  noticed  to  be  now  disputed. 
Gowers '  lays  stress  upon  this  point  in  the  following  words : 
''  The  fact  that  the  patient  may  be  unconscious  of  a  most  sig- 
nificant auditory  defect  lessens  the  value  of  former  observa- 
tions as  evidence  of  the  definite  character  of  stomachal  ver- 
tigo. My  own  conviction  is  that,  in  the  vast  majority  of 
cases  in  which  a  vertigo  of  definite  and  uniform  character  is 
apparently  excited  by  gastric  disturbance,  an  auditory  defect 
will  be  discovered  on  careful  examination." 

Patients  afflicted  with  diseases  of  the  ear  may,  in  some 
cases,  make  themselves  dizzy  by  pressure  upon  the  ear  of  the 
affected  side  ; '  while  oscillatory  movements  of  the  eyes  may 
occasionally  accompany  the  vertigo  dependent  upon  disease 
of  the  acoustic  apparatus. 

It  is  well  known  that  the  semicircular  canals  within  the 
temporal  bone,  when  diseased,  are  liable  to  create  the  so-called 
Meniere's  malady,  in  which  constant  vertigo  is  a  prominent 
symptom  ;  and  experiments  upon  birds  and  animals '  seem  to 
show  that,  in  some  unknown  way,  these  canals  affect  coordi- 
nation of  movement  and  tend  to  preserve  the  equilibrium  of 
the  body. 

When  the  horizontal  canal  of  the  bird  is  cut,  the  head  is 
constantly  moved  from  side  to  side  ;  when  the  posterior  verti- 
cal canal  is  cut,  the  head  is  moved  up  and  down  ;  when  the 
anterior  vertical  canal  is  severed,  the  movement  of  the  head 
is  in  a  diagonal  direction.  If  section  of  either  of  these  canals 
be  made,  upon  both  sides  of  the  head,  the  movements  of  the 
head  above  described  are  permanent ;  but,  if  made  on  one 

»  "Brit.  Med.  Jour.,"  April,  ISYV. 
2  Schwaback,  as  quoted  by  Hughlings-Jackson. 

^Flourens,  1824;  Crum  Brown,  "Jour.  Anat.  Phys.,"  18T4;  Cyon,  "Thfese  pour  le 
doctorat  in  medicine,"  as  quoted  by  Foster. 


216  THE  CRANIAL  NERVES. 

side  only,  they  tend  to  disappear  within  twenty-four  or  forty- 
eight  hours.'  If  the  same  class  of  experiments  be  made  upon 
rabbits,  the  movements  of  the  head  are  less  marked,  but  oscil- 
lating movements  of  the  eyeballs  (nystagmus)  are  developed  ; 
while,  if  made  upon  certain  other  animals,  a  loss  of  coordina- 
tion in  the  movements  of  the  body  and  limbs  is  sometimes 
produced/ 

When  a  person  is  rotated  for  some  time,  a  sense  of  vertigo 
is  produced  ;  and  this  symptom  seems  to  warrant  the  supposi- 
tion that  some  abnormal  effect  is  produced  within  the  semicir- 
cular canals,  through  the  auditory  nerve  filaments,  possibly 
as  a  result  of  concussion  of  the  fluids  of  the  ear  against  the 
bony  wall.' 

The  following  quotation  from  Michael  Foster,*  in  discuss- 
ing the  different  theories  advanced  to  explain  coordination  of 
movement  and  the  various  reflex  phenomena  which  are  con- 
stantly brought  to  the  notice  of  the  physiologist,  seems  par- 
ticularly applicable  to  the  practical  branches  of  medicine : 
''All  day  long,  and  every  day,  multitudinous  afferent  im- 
pulses, from  eye  and  ear,  and  skin  and  muscle,  and  other 
tissues  and  organs,  are  streaming  into  our  nervous  system, 
and,  did  each  afferent  impulse  produce  its  correlative  motor 
impulse,  our  life  would  be  a  prolonged  convulsion.     As  it  is, 

1  E.  Cyon,  ojD.  d<.,  1878. 

2  The  experiments  of  Arthur  Bottcher,  made  in  1872,  seem  to  conflict  with  those  of 
Cyon,  Goltz,  and  Flourens,  as  to  the  function  of  the  semicircular  canals.  He  claims  that 
the  section  of  either  canal  can  be  made  without  causing  any  symptoms  of  incoordination, 
provided  the  auditory  nerve  filaments  are  not  pulled  upon.  The  fact  that  the  auditory 
nerve  is  not  bound  down  at  any  point  between  the  brain  and  the  labyrinth  explains,  ac- 
cording to  this  observer,  why  the  sligMest  traction  upon  it  may  injure  its  attachment  to 
the  medulla,  and  thus  create  the  symptoms  described  by  Cyon,  Goltz,  and  Flourens. 

^  A.  H.  Buck,  in  a  late  treatise,  reiterates  his  former  statement,  that  nerves  are  not 
found  in  the  semicircular  canals,  except  in  the  ampullae.  This  fact  he  adduces  in  sup- 
port of  the  theory  that  they  have  no  relation  to  the  perception  of  sound  impulses.  He 
also  claims  that  the  small  size  of  this  portion  of  the  membranous  labyrinth,  as  compared 
with  the  diameter  of  the  bony  excavation,  coupled  with  the  peculiar  reticulated  arrange- 
ment which  exists  in  the  space  between  the  membranous  tube  and  the  bony  wall,  further 
sustains  his  objection.  This  author  seems  to  claim  that  the  semicircular  canals  act  as  a 
means  of  relief  to  extreme  intra-cochlear  pressure.  Certainly,  more  light  is  needed  upon 
the  construction  of  this  portion  of  the  internal  ear,  before  its  function  can  be  positively 
determined. 

4  Op.  cit. 


FUNCTION  OF  THE  TYMPANIC  MUSCLES.  217 

by  the  checks  and  counter- checks  of  cerebral  and  spinal  activ- 
ities, all  these  impulses  are  drilled  and  marshaled,  and  kept 
in  hand,  in  orderly  array,  till  a  movement  is  called  for ;  and 
thus  we  are  able  to  execute  at  will  the  most  complex  bodily 
manoeuvres,  knowing  only  wJiy^  and  unconscious,  or  but  dimly 
conscious,  how  we  carry  them  out." 

The  tensor  tympani  muscle^  which  has  previously  been 
mentioned  as  deriving  its  motor  power  from  the  fifth  nerve 
and  otic  ganglion,  is  of  use,  even  in  the  quiescent  state,  in 
preventing  the  membrana  tympani  from  being  pushed  too  far 
outward.  During  its  contraction,  the  membranous  drum  of 
the  ear  is  made  tense,  for  the  purpose  of  deadening  some 
sounds  or  of  favoring  the  reception  of  others,  by  bringing  the 
tension  of  the  membrane  in  more  perfect  attune  to  the  sounds 
which  fall  upon  it.  It  may,  therefore,  be  considered  in  some 
respects  as  an  analogue  to  the  ciliary  muscle  of  the  eye, 
since  both  act  as  a  sort  of  accommodation  to  a  mechanism. 
In  some  persons,  this  muscle  is  under  voluntary  control,  and 
thus  a  crackling  sound  may  be  produced  within  the  ear  at 
will,  or  discords  be  produced  when  musical  sounds  are  being 
listened  to. 

The  stapedius  muscle,  which  derives  its  motor  power  from 
the  facial  nerve,  is  supposed  to  regulate  the  movements  of  the 
stapes  (one  of  the  small  bones  of  the  middle  ear),  and  espe- 
cially to  prevent  any  sudden  or  excessive  movement  of  the 
membrana  tympani  from  forcing  its  base  too  far  into  the 
fenestra  ovalis. 

The  Eustachian  tube  is  unquestionably  open  during  the 
act  of  swallowing,  but  it  is  stiU  disputed  whether  it  remains 
permanently  open  or  is  open  at  intervals.  The  swelling  of 
the  mucous  membrane  which  lines  the  tube,  in  catarrhal 
inflammation,  interferes  with  the  entrance  of  air  into  the 
middle  ear,  and  is  frequently  associated  with  that  peculiar 
ringing  or  buzzing  in  the  ear  so  often  present  during  attacks 
of  influenza.  One  of  the  functions  of  this  tube  is  undoubtedly 
to  afford  a  means  of  exit  for  the  secretions  of  the  cavity  of 
the  middle  ear,  and,  in  case  of  inflammation  of  that  cavity, 


218  THE  CRANIAL  NERVES. 

should  the  Eustachain  tube  become  closed,  perforation  of  the 
drum  will  ensue,  when  the  presence  of  the  accumulated  pus 
creates  imperfect  nutrition  of  that  membrane  and  consequent 
ulceration  of  its  coats. 

Waves  of  sound  can  and  do  reach  the  endolymph  of  the 
internal  ear  by  direct  conduction  through  the  skull.  Since, 
however,  sonorous  vibrations  are  transmitted  from  the  air  to 
solids  and  liquids  (and  most  sounds  come  to  us  through  the 
air),  some  special  apparatus  is  required  to  thus  transfer  the 
aerial  vibrations  to  the  fluids  of  the  labyrinth.  The  late  me- 
chanical devices,  recommended  for  the  relief  of  perfect  deaf- 
ness, in  which  the  teeth  are  used  as  a  conducting  medium, 
have  not  as  yet  fulfilled  the  predictions  of  their  inventors. ' 

The  deafness  which  often  follows  suppuration  of  the  mid- 
dle ear  does  not  necessarily  indicate  any  diseased  condition 
of  the  auditory  nerve,  since  it  may  be  the  result  of  perfora- 
tion of  the  memhrana  tympani^^  or  of  an  abnormal  condition 
of  the  hones  of  the  middle  ear,  both  of  which  might  interfere 
most  seriously  with  the  transmission  of  sound. 

Foreign  bodies  in  the  ear  often  create  most  alarming 
symptoms  ;  and  even  an  accumulation  of  wax,  pressing  on  the 
drum,  may  create  a  mental  condition  strongly  resembling  the 
excitement  of  alcohol  or  mania.'  Even  syringing  the  ear  has 
been  known  to  produce  fainting  and  severe  attack  of  audi- 
tory vertigo.  Prolonged  suppuration  of  the  middle  ear  may 
be  the  direct  cause  of  fatal  inflammation  of  the  meninges  of 
the  brain. 

Neuroses  of  the  'acoustic  nerve  are,  of  necessity,  more  ob- 
scure and  difficult  of  detection  than  those  of  the  other  special 


*  It  has  long  been  the  custom  with  otologists  to  use  a  tuning-fork,  placed  upon  the 
forehead  (when  in  vibration),  to  determine  between  disease  of  the  middle  ear  and  that  of 
the  labyrinth ;  since  in  the  former  the  affected  ear  hears  the  tuning-fork  most  plainly, 
while,  in  the  latter,  the  unaffected  ear  hears  it  most  distinctly. 

*  Perforation  of  the  extcT^al  drum  of  the  ear  does  not  necessarily  create  deafness. 
That  remarkable  case,  reported  by  Sir  Astley  Cooper,  when  both  drums  were  nearly  de- 
stroyed and  where  the  patient  could  still  hear  ordinary  conversation,  illustrates  this 
point. 

*  See  case  of  a  louse  in  the  ear,  reported  by  Hughlings-Jackson,  '*  Lancet,"  October, 
1880. 


NEUROSES   OF  THE  AUDITORY  NERVE.  219 

senses ;  since  the  tests  of  normal  sight,  smell,  and  taste  are 
much  more  easy  and  satisfactory  than  the  appreciation  of  the 
faculty  of  a  fine  discrimination  on  the  part  of  the  patient  be- 
tween notes  of  a  different  pitch  and  quality.  To  what  extent 
the  original  and  exhaustive  researches  of  Brenner,*  as  to  the 
value  of  the  galvanic  current  in  the  diagnosis  of  abnormal  con- 
ditions of  the  nerve  filaments  within  the  chambers  of  the  laby- 
rinth, will  be  sustained  by  pathological  and  clinical  investiga- 
tion, it  is  difficult  now  to  say  ;  but  it  certainly  appears  to  shed 
some  light  upon  a  field  of  diagnosis  which  has  been  almost 
unexplored  on  account  of  the  difficulties  which  have  hitherto 
existed.  It  will  exceed  the  scope  of  this  volume  to  enter  into 
the  detail  of  this  new  method,  since  the  principles  of  the 
manifestation  of  the  electric  current  upon  nerve  tissue  would 
have  to  be  explained,  and  the  different  formulae  of  nerve  reac- 
tion given.  It  can,  however,  be  stated  that  the  principle  con- 
sists of  obtaining  certain  sensations  by  means  of  the  auditory- 
nerve  filaments,  when  one  moistened  pole  of  an  electric  bat- 
tery is  placed  upon  the  tragus  or  the  auditory  meatus,  and 
the  other  to  the  back  of  the  neck  or  the  inner  side  of  the 
arm,  and  the  intensity  of  the  current  regulated  by  means  of 
the  rheostat.''  By  this  means  the  condition  of  acoustic  hyper- 
sesthesia  and  of  anaesthesia  may  be  detected  with  an  accuracy 
which  older  methods  could  not  afford. 

The  state  of  acoustic  hyper cesthesia  may  be  of  central 
origin  or  dependent  upon  some  peripheral  cause.  If  due  to 
the  former,  it  may  be  developed  in  connection  with  chronic 
cephalalgia,  hysteria,  insanity,  cerebral  hypersemia,  and  with 
irritative  conditions  of  the  brain  or  spinal  cord.  It  is  some- 
times associated  with  hallucinations  of  hearing,  especially 
if  present  as  a  complication  of  insanity.  The  peripheral 
causes  of  this  condition  comprise  anything  which  can  pro- 
duce an  exaggeration  of  the  tension  of  the  muscles  or  bones 
of  the  middle  ear,  thus  resulting  in  a  constant  compression 
of  the  internal  structures  of  the  labyrinth.  The  experi- 
ments of  Lucae  seem  to  point  to  the  tensor  tympani  mus- 

1  As  discussed  in  detail  by  Erb,  Rosenthal,  and  others.  ^  Erb's  rule. 


220  THE  CRANIAL  NERVES. 

die  as  the  agent  in  accommodating  the  bones  of  the  middle 
ear  to  the  keenest  appreciation  of  musical  tones^  while  the 
stapedius  muscle  presides  over  the  accommodation  for  shriller 
and  non-musical  auditory  sensations.  AVe  can  thus  under- 
stand, if  this  be  true,  how  paralysis  of  the  stapedius  muscle 
would  create  an  hypersesthesia  of  the  acoustic  apparatus,  and, 
as  this  muscle  may  be  affected  in  facial  paralysis,  how  all  of 
the  causes  of  that  condition  may  be  the  exciting  causes  also 
of  this  affection  of  the  ear.' 

The  state  of  ancesthesia  of  the  auditory  nerve  is  always 
associated  with  some  severe  and  persistent  defect  in  hearing, 
since  the  filaments  of  the  auditory  nerve  are  no  longer  able  to 
transmit  the  impressions  of  sound.  Its  causes  are  but  poorly 
understood,  but  it  seems  positive  that  lesions  of  the  posterior 
regions  of  the  meso-cephalon,  the  medulla,  and  cerebellum,  as 
well  as  new  growths  at  the  base  of  the  brain,  excessive  intra- 
cranial pressure,  and  local  disease  of  the  labyrinth  itself,  may 
be  thus  manifested.  The  deafness  which  follows  the  exan- 
thematous  fevers,  and  is  observed  in  hysteria  and  ataxia, 
usually  indicates  changes  in  the  meninges  of  the  brain,  which, 
if  severe,  produce  an  incurable  loss  of  hearing.  Malforma- 
tions of  the  internal  or  middle  ear,  either  congenital,  or  ac- 
quired during  childhood  after  cerebral  diseases,  are  the  com- 
mon causes  of  deaf-mutism. 

THE  GLOSSO-PHARYNGEAL,   OR  NINTH  NERVE. 

Like  the  two  previous  nerves,  both  the  superficial  and 
deep  points  of  origin  of  the  glosso-pharyngeal  nerve  are  situ- 
ated in  the  medulla  oblongata,  a  separate  gray  nucleus  in  the 
floor  of  the  fourth  i^entricle  being  ascribed  to  it."  This  nerve 
escapes  from  a  groove  between  the  lateral  tract  and  the  resti- 
form  body  of  the  medulla,  lying  below  the  auditory  nerve 
and  above  the  pneumogastric,  and  passes  out  of  the  cavity  of 

'  This  may  be  deemed  incompatible  with  statements  made  on  page  194  of  this  vol- 
ume, as  the  tensor  tympani  muscle  was  there  stated  to  be  an  agent  in  creating  auditory 
defect  in  Bell's  paralysis. 

'  Ferrier,  "  Functions  of  the  Brain,"  London,  1876. 


THE   GLOSSO-PHARYNGEAL,   OR  NINTH  NERVE.        221 

the  cranium  by  the  jugular  foramen,  where  it  lies  in  close 
relation  with  the  pneumogastric  and  spinal  accessory  nerves, 
the  jugular  vein,  and  the  inferior  meningeal  artery.  It  pos- 
sesses motor  and  sensory  fibers,  and  fibers  which  assist  in 
the  appreciation  of  the  special  sense  of  taste. 


,....  -..-.J 


Fig.  19. —  Glosso-pharyngeal  nerve.      (Sappey.) 

1,  large  root  of  the  fifth  nerve ;  2,  ganglion  of  Gasser  ;  3,  ophthalmic  division  of  the  fifth  ; 
4,  superior  maxillary  division ;  5,  inferior  maxillary  division ;  6,  10,  lingual  branch 
of  the  fifth,  containing  the  filaments  of  the  chorda  tympani;  7,  branch  from  the  sub- 
lingual to  the  lingual  branch  of  the  fifth ;  8,  chorda  tympani ;  9,  inferior  dental 
nerve;  10,  terminal  filaments  of  the  lingual  nerve;  11,  submaxillary  ganglion ;  12, 
mylo-hyoid  branch  of  the  inferior  dental  nerve;  13,  anterior  belly  of  the  digastric 
muscle;  14,  section  of  the  mylo-hyoid  muscle;  15,  18,  glosso-pharyngeal  nerve;  16, 
ganglion  of  Andersch  ;  17,  branches  from  the  glosso-pharyngeal  to  the  stylo-glossus 
and  the  stylo-pharyngeus  muscles;  19,  19,  pneumogastric;  20,  21,  ganglia  of  the 
pneumogastric;  22,  22,  superior  laryngeal  nerve;  23,  spinal  accessory;  24,  25,  26, 
27,  28,  sublingual  nerve  and  branches. 

By  reference  to  the  diagram,'  it  will  be  perceived  that  two 
ganglioform  enlargements  are  developed  upon  this  nerve,  the 
upper  one  being  situated  on  a  level  of  the  upper  opening  of 

'  See  Fig.  80,  on  the  following  page. 


222 


THE  CRANIAL  NERVES. 


the  jugular  foramen,  while  the 
I 


Fig.  80. — A  diagram  of  tJie  branches  of 
the  ninth  cranial  or  glosso-pharyn- 
geal  nerve. 

1,  filaments  of  origin,  extending  into 
the  medulla  oblongata ;  2,  the  jug- 
ular  foramen,  through  which  the 
nerve  escapes  from  the  cranium ; 
8,  the  jugular  ganglion,  developed 
upon  the  nerve  in  the  jugular  fora- 
men ;  4,  the  ganglion  of  Andersch, 
or  the  ^^ petrous  ganglion  "/  5,  the 
auricular  branch,  deriving  a  fila- 
ment also  from  the  pneumogastric 
nerve ;  6,  a  communicating  branch 
to  the  pneumogastric  nerve;  7,  a 
communicating  branch  to  the  sym- 
pathetic nerve;  8,  the  tympanic 
branch  or  "  Jacobson's  nerve,^^  dis- 
tributed to  the  middle  ear;  9,  a 
communicating  branch  to  the  carot- 
id plexus  of  the  sympathetic ;  10, 
the  tonsillar  brandies,  distributed 
to  the  tonsil ;  11,  a  portion  of  the 
plmryngeal  plexus,  formed  also  by 
the  pneumogastric  nerve;  12,  the 
lingual  branches,  distributed  to  the 
mucous  membrane  and  the  papillae 
of  the  base  and  sides  of  the  tongue. 


lower  one  lies  slightly  below  the 
foramen.  To  the  first,  the  name 
''  jugular  ganglion  "  is  ap- 
plied, while  the  second  is  called 
the  '' ganglion  of  Anderscli^^^ 
after  its  discoverer.  These  two 
ganglia  do  not  include  the  same 
relative  proportion  of  nerve  fibers 
derived  from  the  glosso-pharyn- 
geal,  since  the  jugular  ganglion 
is  developed  upon  only  a  por- 
tion of  the  nerve,  while  the 
ganglion  of  Andersch  includes 
all  the  filaments  of  the  trunk  of 
that  nerve. 

Within  the  jugular  foramen, 
the  glosso-pharyngeal  nerve  lies 
in  front  of  the  spinal  accessory 
and  pneumogastric  nerves,  which 
are  separated  f  rona  it  by  a  sheath 
which  invests  the  two  latter,  and 
it  bears  an  intimate  relation  with 
the  jugular  vein  within  the  fora- 
men, and  also  in  the  neck. 

As  a  motor  nerve^''  the  glosso- 
pharyngeal supplies  the  levator 
palati,  azygos  uvulae,"  stylo- 
pharyngeus,  and  the  middle 
constrictor  of  the  pharynx ; 
while,  as  a  nerve  of  general  sen- 

^  It  is  extremely  doubtful  if  the  glosso- 
pharyngeal nerve  possesses  any  motor  fiber- 
which  are  not  derived  from  other  nerves  by 
filaments  of  communication. 

'  These  muscles,  if  supplied  by  this  nerve 
(as  experiments  seem  to  show),  are  reached 
by  fibers  sent  to  the  facial  nerve,  and  after- 
ward, by  means  of  the  great  petrosal  branch, 
to  Meckel's  ganglion. 


DISTRIBUTION   OF  GLOSSO-PHARYNQEAL  NERVE.       223 

sation^  it  supplies  the  root  of  the  tongue,  the  soft  palate,  the 
pharynx,  the  Eustachian  tube,  and  the  tympanum.  It  will  be 
thus  perceived  that  the  glosso-pharyngeal  nerve  possesses. 


Fig.  81. — PapillcB  of  the  tongue.    (Sappey.) 

1,  1,  circumvallate  papillae;  2,  median  circumvallate  papilla,  which  entirely  fills  the  fora- 
men caecum ;  3,  3,  3,  3,  fungiform  papillae  ;  4,  4,  filiform  papillae ;  5,  5,  vertical 
folds  and  furrows  of  the  border  of  the  tongue  ;  6,  6,  6,  6,  glands  at  the  base  of  the 
tongue ;  7,  7,  tonsils ;  8,  epiglottis  ;  9,  median  glosso-epiglottidean  fold. 

within  itself^  all  the  necessary  fibers  to  insure  those  succes- 
sive acts  of  a  reflex  type  which  occur  during    deglutition,' 

^  It  is  denied  by  some  physiologists  that  the  sensory  filaments^  which  are  the  main 
agents  in  exciting  the  reflex  acts  perceived  during  deglutition,  are  those  of  the  glosso- 
pharyngeal nerve ;  since  the  sensory  filaments  of  the  fifth  nerve  distributed  to  the  palate 
and  pharynx  from  Meckel's  ganglion  seem  to  also  fulfill  that  important  function. 


224 


THE   CRANIAL  NERVES. 


and  it  is  by  this  nerve  that  the  second  act  of  deglutition  is 
chiefly  excited  and  performed. 

The  sense  of  taste^  which  is  afforded  by  the  glosso-pharyn- 
geal,  is  confined  to  the  posterior  third  of  the  tongue.  A  sim- 
ilar distribution  of  its  sensory  fibers  is  remarkably  illustrated 
in  that  case  of  Hilton's/  where  an  attack  of  tonsillitis  pro- 
duced a  sympathetic  furring  of  the  posterior  third  only  of 
the  lateral  half  of  the  tongue. 

Though  analogy  would  lead  us  to  suppose  that  a  stimulus 
applied  to  any  part  of  the  course  of  the  gustatory  fibers  of  the 
glosso-pharyngeal  nerve  would  give  rise  to  a  sensation  of 
taste  and  nothing  else,  the  proof  is  not  forthcoming ;  since 
this  nerve,  as  before  stated,  is  a  mixed  nerve  containing  sen- 
sory fibers  as  well  as  those  of  taste. 


Fig.  82.  Fig.  83. 

Varieties  of  papillce  of  the  tongtte.     (Sappey.) 

Fig.  82. — Medium-sized  circumvallate  papilla:  1,  papilla,  the  base  only  being  apparent : 
it  is  seen  that  the  base  is  covered  with  secondary  papillae ;  2,  groove  between  the 
papilla  and  the  surrounding  wall ;  3,  3,  wall  of  the  papilla. 

Fig.  83. — Fungiform,  filiform,  and  hemispherical  papillae:  1,  1,  two  fungiform  papilla?, 
covered  with  secondary  papillae ;  2,  2,  2,  filiform  papillae ;  3,  a  filiform  papilla,  the 
prolongations  of  which  are  turned  outward  ;  4,  a  filiform  papilla,  with  vertical  pro- 
longations ;  5,  5,  small  filiform  papillas,  with  the  prolongations  turned  inward ;  6,  6, 
filiform  papillae,  with  striations  at  their  bases ;  7,  7,  hemispherical  papillae,  slightl\ 
apparent,  situated  between  the  fungiform  and  the  filiform  papillae. 

Bitter  substances  are  most  tasted  upon  the  haclc  of  tin 
tongue^  and  sweet  substances  when  placed  npon  the  tip; 
a  point  not  without  value  in  administering  medicines.     The 

'  "  Rest  and  Pain."     For  similar  effects  due  to  the  fifth  nerve,  see  a  previous  lecture. 
'^  Mich.  Foster,  op  cit. 


FUNCTIONS  OF  GLOSSO-PHARYNGEAL  NERVE.         225 

so-called  "gustatory  buds,"  which  by  some  have  been  re- 
garded as  specific  organs  of  taste,  are  found  also  upon  the 
epiglottis,  which  is  wholly  devoid  of  taste  ;  hence  their  func- 
tion can  not  as  yet  be  considered  as  fully  determined. 

As  a  means  of  refreshing  your  memory,  the  following 
classification  of  the  branches  of  the  glosso-pharyngeal  nerve 
may  prove  of  value.  It  will  be  seen  that  the  tympanic  branch, 
or  Jacobson's  nerve,  is  specially  important,  since  it  supplies 
portions  of  the  middle  ear  which  have  been  studied,  when  the 
auditory  nerve  was  discussed,  in  their  relation  to  the  mechan- 
ism of  hearing ;  and  also  because  it  gives  a  filament  to  two 
of  the  petrosal  nerves,  whose  functions  have  been  considered 
in  connection  with  the  seventh  cranial  nerve.* 


A  TABLE   OF  THE   BKANCHES  OF  THE  GLOSSO-PHARYNGEAL  KERVE 


1.  Tympanic  branch,  or 
Jacobson^s  nerve. 


Glosso-pharyngeal 
(Ninth  Cranial)      ■> 
Nerve, 


rommunicaiina  f  Large  petrosal  nerve, 
filaments  to     ^  g^^„  petrosal  nerve. 

r>„„„  .  ^„  ^f      f  Fenestra  ovalis, 
Branches  of      I  j,^^^^^^^  ^^^^^^ 

duirzbutton  to   ]  Eustachian  tube. 


2.  Carotid  branches. 

3.  Pharyngeal  branches  (help  to  form  the  pharyngeal  plexus). 

4.  Muscular  branches  (to  muscles  of  the  pharynx). 

5.  Tonsillar  branches  (help  to  form  the  tonsillar  plexus). 

6.  Lingual  branches. 


EFFECTS   OF   SECTION^. 

Section  of  the  glosso-pharyngeal  nerve  is  followed  by  a  type 
of  paralysis,  in  which  deglutition  becomes  an  act  of  extreme 
difiiculty,  and  in  which  regurgitation  of  food  into  the  nostril 
is  particularly  liable  to  occur.  The  sense  of  taste  in  the  pos- 
terior third  of  the  tongue  is  furthermore  completely  destroyed, 
thus  tending  to  prove  that  the  gustatory  fibers  are  inJierent  to 
the  nerve  itself,  and  not  the  result  of  a  communication  between 

^  Flint  ascribes  to  the  chorda  tympani  nei-ve  the  ability  to  perceive  only  saline,  acid, 
and  styptic  qualities ;  and  to  the  glosso-pharyngeal  nei've,  the  appreciation  of  sioeet,  alka- 
line, bitter,  and  metallic  tastes. 

2  Copied  from  the  "  Essentials  of  Anatomy  "  (Darling  and  Ranney).  Putnam's  Sons, 
New  York,  1880. 


226 


THE  CRANIAL  NERVES. 


it  and  some  other  nerve,  as  is  claimed  in  reference  to  the  gus- 
tatory fibers  of  the  fifth. ' 

It  is  stated,  by  some  of  the  later  investigators  upon  this 
subject,  that  the  sense  of  taste  is  not  alone  confined  to  the 
tongue,  but  exists  also  in  the  pillars  of  the  fauces  and  the 
walls  of  the  pharynx^  and  that  section  of  the  glosso-pharyn- 
geal  nerve  causes  an  entire  abolition  of  this  power  of  special 
sense  in  these  latter  regions,  as  well  as  in  the  posterior  third 
of  the  tongue." 

THE   ACT   OF   DEGLUTITION  AKD   ITS  MECHANISM. 

The  act  of  deglutition  is,  perhaps,  more  properly  con- 
nected with  the  glosso-pharyngeal  nerve  than  with  any  other, 
although  that  nerve  assists  in  the  performance  of  one  stage 
only  of  the  entire  act.  For  convenience  of  description,  it  has 
been  the  custom  of  physiologists  to  divide  the  act  of  degluti- 
tion into  three  distinct  periods.     The  first  period,  comprising 


Fig.  84. —  Taste  buds  from  the  lateral  taste  organ  of  the  rabbit.     (Engelmann.) 

the  passage  of  the  bolus  of  food  through  the  mouth,  which  is 
under  the  control  of  the  voluntary  muscles  ;  the  second,  the 
passage  of  the  bolus  through  the  isthmus  of  the  fauces  and 
the  pharynx  ;  the  third,  the  passage  through  the  oesophagus 
to  the  cavity  of  the  stomach. 

In  the  first  period,  the  food  is  first  seized  by  the  lips,  then 

'  See  previous  lecture  on  the  fifth  nerve,  and  also  the  lecture  upon  the  facial  nerve. 

'  Experiments  seem  to  point  to  the  fungiform  and  circumvallate  papillce  of  the  tongue 
as  the  chief  agents  in  perceiving  taste,  if  the  "  taste  buds  "  of  Lo\v6n  and  Schwalbe  are 
accepted  as  proven.    See  Fig.  84. 


THE  PHYSIOLOGY  OF  DEGLUTITION.  227 

forced  between  the  jaws  by  the  tongue  and  the  buccinator 
muscles  ;  and  by  the  teeth  it  is  not  only  masticated,  but  is 
also  mixed  with  the  salivary  secretion.  When  the  food  is 
ready  to  be  swallowed,  the  mouth  is  first  closed,  as  the  act  is 
performed  with  extreme  difficulty  when  the  mouth  is  open,  be- 
cause the  tongue  can  not  properly  act  upon  the  bolus.'  The 
tongue  now  becomes  widened,  so  as  to  offer  a  large  surface 
to  the  bolus  of  food,  and,  with  the  bolus  placed  behind  it,  is 
pressed  backward  along  the  roof  of  the  mouth.  In  case  the 
food  to  be  swallowed  happens  to  be  in  a  liquid  form,  the 
tongue  is  so  curved  that  its  edges  curl  upward,  while  its 
dorsum  is  depressed  in  the  center,  thus  forming  a  longitu- 
dinal groove  along  its  entire  length ;  and  the  soft  palate  is 
so  closely  applied  to  the  base  of  the  tongue  as  to  admit  of  a 
sucking  force. 

The  importance  of  the  tongue  during  this  period  of  the  act 
of  swallowing  can  not  be  overestimated.  Animals,  in  which 
the  tongue  has  been  paralyzed  by  section  of  the  nerves  of  that 
organ,  exhibit  the  utmost  distress  in  their  efforts  to  bring  the 
food  to  the  back  portion  of  the  mouth,  and  are  forced  to  so 
toss  the  head  as  to  bring  the  force  of  gravity  to  their  aid." 
Drinking,  also,  becomes  even  more  interfered  with,  and  the 
tongue  is  no  longer  used  to  help  in  the  act ;  hence,  various 
devices  are  used  to  bring  the  fluid  where  the  reflex  act  of  the 
fauces  will  help  to  carry  it  to  the  stomach.  If  it  were  not  for 
the  fact  that,  after  removal  of  the  tongue  for  local  disease, 
the  stump  was  of  sufficient  length  to  be  of  great  assistance  in 
controlling  the  bolus  of  food,  such  an  operation  would  be  a 
questionable  procedure  in  surgery. 

It  may  be  noticed,  by  those  of  you  who  have  been  follow- 
ing these  remarks  with  care,  that  the  glosso-pharyngeal  nerve 
has,  as  yet,  had  no  influence  upon  the  mechanism  of  degluti- 
tion, since  the  buccinator  muscles  are  supplied  by  the  facial 
nerve,  and  the  tongue  by  the  hypo-glossal  nerves,  which  have 

*  For  the  clinical  proof  of  this  fact,  the  reader  is  referred  to  the  effects  of  "facial 
diplegia."     See  page  197. 

2  We  see  this  also  marked,  but  to  a  less  extent,  in  patients  afOicted  with  glosso-labial 

paralysis. 


228 


THE  CRANIAL  NERVES. 


not,  as  yet,  been  described  ;  but,  as  the  second  and  third 
periods  of  the  act  are  the  most  complex,  and  the  second  most 
completely  under  the  control  of  that  nerve,  the  omission  of 
the  mechanism  of  the  first  period,  until  the  whole  could  be 
considered  together,  was  for  the  purpose  of  making  the  sub- 


FiG.  85. — Cavities  of  the  mouth  and  pharynx,  etc.     (Sappey.) 

Section  in  the  median  line  of  the  face  and  the  superior  portion  of  the  neck,  designed  to 
show  the  mouth  in  its  relations  to  the  nasal  fossae,  the  pharynx,  and  the  larynx :  1, 
sphenoidal  sinuses ;  2,  internal  orifice  of  the  Eustachian  tube ;  8,  palatine  arch ;  4, 
velum  pendulum  palati ;  5,  anterior  pillar  of  the  soft  palate ;  6,  posterior  pillar  of 
the  soft  palate  ;  V,  tonsil ;  8,  lingual  portion  of  the  cavity  of  the  pharynx  ;  9,  epi- 
glottis ;  10,  section  of  the  hyoid  bone  ;  11,  laryngeal  portion  of  the  cavity  of  the 
pharynx;   12,  cavity  of  the  larynx. 


ject  more  easy  of  comprehension  than  if  the  different  periods 
were  considered  separately  from  each  other.  The  effect  of 
section  of  the  inferior  maxillary  branch  of  the  fifth  nerve 
upon  the  act  of  deglutition  has  been  mentioned  in  a  previous 
lecture,  but  this  effect  is  due,  not  alone  to  an  absence  of  the 


THE  PHYSIOLOGY  OF  DEGLUTITION, 


229 


normal  muscular  power  of  the  muscles  of  mastication,  but 
also  to  an  anaesthetic  condition  of  the  mucous  lining  of  the 
mouth,  which  renders  the  tongue  unable  to  appreciate  the 
situation  of  the  bolus  of  food  ;  as  has  been  proven  by  the  fact 
that  the  same  difficulty  exists  when  section  of  the  fifth  nerve 
is  made  in  front  of  the  ganglion  of  Gasser,  where  only  the 
sensory  portion  of  the  nerve  can  be  injured,  as  when  both  the 
motor  and  sensory  portions  of  the  nerve  are  involved,  after 
section  below  the  foramen  ovale. 

In  the  second  period  of  deglutition,  the  bolus  of  food, 
by  being  crowded  backward,  tends  to  raise  the  soft  palate ; 
and  the  levator  palati  muscle  further  assists  in  retaining  the 
palate  in  this  elevated  position,  while  the  superior  constric- 
tor muscle  of  the  pharynx  causes  the  posterior  wall  of  the 
pharynx  to  bulge  forward,  and  thus  to  meet  the  uvula.  The 
posterior  nasal  openings  are  thus  mechanically  closed  to  the 
entrance  of  the  food  into  the  chamber  of  the  nose,  prepara- 
tory to  the  series  of  reflex  movements  which  are  to  ensue,  for 
the  purpose  of  forcing  the  bolus  downward  into  the  oesopha- 
gus, and  thence  into  the  stomach. 

The  larynx  is  now  suddenly  raised^  so  as  to  bring  the 
superior  opening  of  that  organ  underneath  the  base  of  the 
tongue,  which  has  been  crowded  backward  during  the  first 
period,  in  order  to  force  the  bolus  against  the  soft  palate. 
Its  soft  structure  renders  it  admirably  adapted  to  mold  itself 
to  the  irregularities  of  outline  of  the  laryngeal  opening.  By 
this  position  of  the  tongue,  the  epiglottis  is  also  applied  over 
this  opening,'  and  the  entrance  of  food  into  the  larynx  is 
furthermore  guarded  against  by  the  approximation  of  the 
vocal  cords  by  means  of  the  adductor  muscles  of  the  larynx. 
The  muscles  which  thus  raise  the  larynx  are  the  anterior 
belly  of  the  digastric,  the  mylo-hyoid,  the  genio-hyoid,  the 
stylo-glossus,  and  some  of  the  fibers  of  the  genio-glossus. 

Simultaneously  with  the  elevation  of  the  larynx,  the  pa- 

'  It  was  formerly  supposed  that  the  epiglottis  was  the  chief  instrument  in  prevent- 
ing the  entrance  of  food  into  the  larynx,  but  the  large  number  of  cases  where  the 
epiglottis  has  been  removed,  and  no  difficulty  in  deglutition  apparently  produced,  have 
created  a  doubt  as  to  its  importance. 

ir 


2^0 


THE  CRANIAL  NERVES. 


lato-pharyngeal  muscles  contract  and  raise  the  lower  end  of 
the  pharynx^  thus  shortening  the  length  of  that  organ  and 
tending  to  draw  the  pharynx  over  the  bolus  of  food,  very 
much  as  a  glove  is  drawn  over  the  finger ;  while,  at  the  same 
time,  the  curve  of  the  posterior  pillars   of  the  pharynx  is 


Fig.  86. — Muscles  of  tlie pharifnx,  etc.     (Sappey.) 

1,  2,  3,  4,  4,  superior  constrictor  ;  5,  6,  7, 8,  middle  constrictor ;  9,  10,  11,  12,  inferior  con- 
strictor; 13,  13,  stylo-pharyngeus ;  14,  stylo-hyoid  muscle;  16,  stylo-glossus ;  16, 
hyo-glossus;  17,  mylo-hyoid  muscle;  18,  buccinator  muscle;  19,  tensor  palati ;  20, 
levator  palati. 


made  straight,  and,  by  the  approximation  of  these  muscles 
to  the  sides  of  the  uvula,  the  opening  of  the  pharynx  into 
the  nares  is  now  completely  occluded. 

The  constrictor  muscles  of  the  pharynx  now  come  into 


THi:  PHYSIOLOGY  OF  DEGLUTITION.  231 

play,  contracting  in  succession  from  above  downward ;  the 
posterior  pillars  of  the  fauces,  by  their  approximation,  pre- 
vent the  bolus  from  again  entering  the  mouth  ;  and  it  is  thus 
forced  to  enter  the  oesophagus. 

It  is  apparent  that  most  of  these  movements  are  of  a  re- 
^fl£x  character,  and  are  excited  by  the  presence  of  the  bolus 
Bf  food,  which  passes  out  of  voluntary  control  as  soon  as  it 
passes  the  anterior  pillar  of  the  fauces,  at  which  point  the 
second  period  of  deglutition  may  be  said  to  commence.  Every 
reflex  act  presupposes  some  sensory  filaments  to  convey  the 
impression  to  the  brain,  and  certain  motor  filaments  to  trans- 
mit the  impulses  to  the  muscles  destined  to  act  upon  the 
bolus ;  it  is  now  believed  that  the  ^losso-pharyngeal  nerve 
possesses  both  of  these  sets  of  fibers,  as  well  as  those  control- 
ling the  special  sense  of  taste.  This  nerve  may  then  be  con- 
sidered as  a  nerve  of  taste,  a  nerve  of  motion  to  the  pharyn- 
geal muscles,  and  the  true  ''excitory  nerve^^  of  the  act  of 
deglutition. 

The  importance  of  the  soft  palate  in  the  act  of  deglutition 
is  particularly  shown  during  the  swallowing  of  liquids,  since 
it  has  to  be  closely  applied  to  the  base  of  the  tongue,  in  order 
to  allow  of  a  partial  vacuum  within  the  cavity  of  the  mouth, 
and  thus  to  draw  the  fluid  along  the  furrow  formed  by  the 
curving  upward  of  the  edges  of  the  tongue.  This  fact  is  clin- 
ically shown  by  patients  affected  with  paralysis  of  the  velum,' 
who  experience  great  difficulty  in  swallowing  liquids,  since 
the  fluid  is  liable  to  escape  through  the  nose.  A  case  of  this 
character  is  reported  by  Berard,  where  a  young  lady  was 
obliged  to  free  herself  from  all  observation  whenever  she  at- 
tempted to  drink,  as  the  escape  by  the  nostrils  was  so  profuse 
as  to  occasion  embarrassment. 

The  prevention  of  the  entrance  of  food  into  the  cavity  of 
the  larynx,  as  has  been  mentioned,  is  insured :  first,  by  the 
base  of  the  tongue  ;  secondly,  by  the  epiglottis  ;  and,  thirdly, 

>  Paralysis  of  certain  muscles  of  the  soft  palate  occurs  when  t\ve  facial  nerve  is  im- 
paired behind  the  point  of  origin  of  its  petrosal  branches.  For  particulars  of  this  diag- 
nostic symptom,  the  reader  is  referred  to  page  194. 


232  THE  CRANIAL  NERVES. 

by  the  approximation  of  the  vocal  cords  ;  but  that  such  acci- 
dents do  still  happen  from  attempts  at  inspiration '  during 
eating  is  attested  by  the  violent  coughing  excited,  and  by 
the  instantaneous  expulsion  of  the  foreign  substance,  unless 
it  should  chance  to  become  mechanically  arrested  in  the  larynx. 
Longet  accounts  for  the  symptoms  excited  by  such  an  acci- 
dent as  the  result  of  an  exquisite  sensibility  possessed  by  the 
mucous  lining  of  the  upper  part  of  the  larynx.  It  is  well 
attested  that  the  danger  of  entrance  of  fluids  into  this  organ 
is  far  greater  than  in  the  case  of  solids ;  and  the  act  of  gar- 
gling is  especially  liable  to  be  followed  by  such  an  occurrence, 
since  the  larynx  is  much  wider  open  than  in  the  act  of  deglu- 
tition. In  the  administration  of  anaesthetics  to  patients  who 
have  eaten  largely  before  the  hour  appointed  for  surgical^ 
relief,  a  great  danger  of  the  entrance  of  vomited  matters 
into  the  cavity  of  the  larynx  is  encountered,  since  the  sensi- 
tiveness of  the  mucous  lining  is  destroyed,  and  the  expulsive 
efforts  of  Nature  are  often  wanting.' 

The  third  period  of  the  act  of  deglutition  is  confined  t< 
the  oesophagus,  through  which  the  bolus  has  to  pass  to  read 
the  stomach.  The  downward  movement  of  the  bolus  is  as- 
sisted by  alternate  contraction  of  the  longitudinal  fibers  oi 
the  tube,  which  shorten  it  and  tend  to  draw  its  walls  upward 
over  the  bolus,  and  contraction  of  the  circular  fibers,  which 
constrict  the  tube  and  force  the  bolus  downward.  The  fact 
that  gravity  has  little,  if  anything,  to  do  with  this  downward 
movement  is  proven  by  the  fact  that  the  position  of  the  body 
does  not  seem  to  affect  it,  while  acrobats  are  often  known  to 
perform  the  feat  while  standing  upon  the  head  or  hands.  The 
time  consumed  in  the  passage  through  the  oesophagus  was 
estimated  by  Magendie "  as  about  two  minutes  in  animals,  but 

^  As  occurs  during  attacks  of  laughing,  hiccough,  etc.,  when  food  is  present  in  tlic 
mouth,  or  during  too  hasty  an  effort  to  consume  food. 

^  In  cases  where  this  accident  occurs,  the  tongue  should  be  forcibly  drawn  out  of  the 
mouth,  80  as  to  pull  up  the  epiglottis,  and  the  foreign  body  extracted  by  the  finger,  if 
possible,  or,  if  not,  the  patient  should  be  held  by  the  feet,  and  thus,  by  shaking  the  pa- 
tient, gravity  may  help  to  dislodge  it.  I  once  saved  the  life  of  a  man  by  this  means 
when  all  others  had  failed,  and  fatal  asphyxia  seemed  imminent. 

^  "  Journal  de  Physiol." 


THE  PHYSIOLOGY  OF  DEGLUTITION.  233 

it  is  probably  much  shorter  in  man ;  although  we  are  often 
conscious  of  a  delayed  termination  of  the  act,  and  are  forced 
to  hasten  it  by  the  drinking  of  fluids,  as  most  of  us  can  attest. 
It  is  probable  that  this  peristaltic  action  of  the  oesophagus, 
like  that  of  the  intestinal  canal,  is  partly  controlled  by  the 
nervous  influence  of  the  sympathetic  system,  although  the 
pneumogastric  nerves  have  an  extensive  distribution  to  and 
a  very  marked  control  over  this  organ/ 

Deglutition  is  essentially  a  reflex  act^  save  in  its  first 
period,  when  volition  plays  an  important  part.  It  can  not 
take  place  unless  some  stimulus  is  applied  to  the  mucous 
lining  of  the  fauces  ;  and  those  apparently  voluntary  acts  of 
deglutition  which  are  produced  when  no  food  is  within  the 
mouth  are  undoubtedly  due  to  the  swallowing  of  saliva,  or 
to  irritation  of  the  fauces  by  the  base  of  the  tongue  itself. 
When  we  tickle  the  fauces,  we  can  see  all  of  the  act  of  deglu- 
tition, confined  to  the  second  period,  artificially  produced  ; 
and  this  irritability  of  the  fauces  is  so  extreme  in  some  per- 
sons as  to  render  any  attempt  to  examine  the  throat  one  of 
difficulty,  and  often  a  cause  of  reflex  vomiting.  So  impor- 
tant is  the  education  of  the  throat  to  enable  the  patient  to 
tolerate  the  presence  of  instruments,  that  all  surgical  proced- 
ures upon  the  larynx,  if  performed  from  within  the  mouth, 
require  often  months  of  training  to  enable  the  patient  to  assist 
the  operator  in  a  step  whose  execution  may  be  a  matter  of  a 
few  seconds  only.  All  forms  of  local  applications  are  used 
to  insure  an  anaesthetic  condition  of  these  parts,  and  the  in- 
ternal administration  of  medicinal  agents  is,  furthermore, 
often  required  to  render  such  procedures  within  the  cavity 
of  the  larynx  possible. 

That  the  center  for  the  reflex  act  of  deglutition  is  confined 
to  the  medulla  oblongata  is  proven  by  experiment  on  animals 
whose  brain  has  been  entirely  removed,  with  the  exception  of 
the  medulla,  when  irritation  of  i^ie  fauces  will  still  continue 

^  Michael  Foster  regards  this  third  act  of  degUitition  as  more  closely  dependent  upon 
the  central  nervous  system  than  the  movements  of  the  intestinal  tract,  and  attributes  it  to 
reflex  action  due  to  the  bolus. 


234  THE  CRANIAL  NERVES. 

to  produce  all  the  movements  of  the  second  stage  of  that 
act. 

CLINICAL   POINTS   OF   INTEREST   PERTAINING  TO  THE  GLOSSO-PHARYN- 

GEAL   NERVE. 

The  intimate  association  which  apparently  exists  between 
the  fibers  of  this  nerve  and  the  sense  of  taste,  the  movements 
of  the  pharyngeal  muscles,  and  the  reflex  acts  excited  by  the 
presence  of  a  bolus  or  of  some  foreign  source  of  irritation  to 
the  isthmus  of  the  fauces  and  the  walls  of  the  pharynx,  would 
seem  to  suggest  that  any  impairment  of  the  glosso-pharyngeal 
would  be  followed  by  clinical  evidences  of  imperfect  perform- 
ance of  each  and  all  of  these  functions.  It  is,  however,  to  be 
regretted  that  the  questions  of  the  course,  origin,  and  func- 
tions of  the  chorda  tympani  nerve,  the  exact  distribution  of 
the  fibers  of  the  glosso-pharyngeal  nerve  to  the  tongue,  and 
the  source  from  which  this  latter  nerve  derives  its  motor  fila- 
ments, are,  as  yet,  disputed  points  among  physiologists  ;  and 
the  sources  of  doubt  are  not  removed,  but  rather  increased,  by 
the  results  of  pathological  observation,  since  they  often  seem 
contradictory,  and  thus  prove  rather  a  source  of  embarass- 
ment  than  an  aid  to  definite  conclusions. 

One  would  naturally  suppose,  provided  that  he  was  fa- 
miliar with  the  symptoms  of  that  disease,  called  by  Duchenne 
''glosso-labio-laryngeal  paralysis"  (although  the  word  *' pha- 
ryngeal" is  often  used  in  place  of  ''laryngeal"  to  express  the 
same  condition),  that  the  difficulty  experienced  in  deglutition 
would  certainly  indicate  that  the  nerve  which  apparently  pre- 
sides over  that  function  would  be  found  in  a  state  of  disease  ; 
but,  on  the  contrary,  the  glosso-pharyngeal  nerve  is  not  re- 
ported, to  my  knowledge,  as  having  anything  to  do  with  that 
affection.  We  must,  therefore,  be  forced  to  infer  that  the 
motor  filaments  of  the  pharynx  are,  to  a  great  extent,  con- 
trolled by  other  nerves  ;  and  that,  if  they  are  apparently 
branches  of  the  ninth  cranial  nerve,  they  are  to  be  accounted 
for  as  fibers  derived  from  communicating  filaments  from  other 
sources. 


CLINICAL    CONDITIONS   CAUSING  HYPERGEUSIA.      235 

Hirsclifeld  claims  to  have  verified  a  branch  of  the  glosso- 
pharyngeal nerve  which  extends  to  the  anterior  two  thirds  of 
the  tongue ;  hence  the  strong  probability  that  it  partially 
controls  the  sense  of  taste  in  that  portion  as  well  as  in  the 
posterior  third  of  the  organ.  Stannius,  by  experiments, 
thinks  that  he  has  established  the  function  of  this  branch, 
and  he  attributes  to  it  the  power  of  perception  of  Mtter 
substances  only,  the  other  varieties  of  taste  sensations 
being  presided  over  by  the  chorda  tympani  nerve  or  the 
gustatory  branch  of  the  fifth  nerve.  We  know,  clinically, 
that  the  conditions  of  hypersesthesia  and  anaesthesia  of 
the  gustatory  nerves  are  verified  by  many  interesting  phe- 
nomena ;  and  we  must  be  content  to  wait  for  the  solution 
of  the  other  mixed  problems  of  gustation,  until  they  are 
solved  by  further  clinical,  physiological,  and  pathological 
observation. 

The  condition  of  gustatory  hyper cesthesia^  called  also 
^^ hyper geusia^^^ '  is  very  marked  in  certain  patients  who  are 
in  an  anaemic  and  nervous  condition,  while  it  is  a  frequent 
phenomenon  in  hysteria  and  in  melancholia.  In  such  cases 
an  apparent  gustatory  sensation  may  be  often  excited  by  the 
application  of  an  electric  current  .to  the  cervical  or  upper 
dorsal  region  of  the  spine. 

True  gustatory  hypersesthesia  may  express  itself  as  an  in- 
crease in  the  delicacy  of  the  gustatory  sensation,  so  that  ex- 
tremely small  quantities  of  sapid  substances  may  be  perceived. 
We  thus  occasionally  meet  with  hysterical  patients,  who  can 
perceive  the  taste  of  certain  medicinal  agents  in  a  solution 
which  to  the  healthy  subject  would  be  tasteless.  It  may  ex- 
press itself,  again,  as  an  unnatural  enjoyment  of  food,  or  a 
loathing  of  certain  dishes  which  convey  a  sense  of  taste  which 
does  not  in  reality  exist.  In  facial  paralysis  of  rheumatic 
origin,  abnormal  gustatory  sensations  are  sometimes  present, 
as  sweetish,  sour,  or  sapid  tastes,  within  the  mouth.  In  the 
insane,  hallucinations  of  the  special  sense  of  taste,  usually  of 

^  See  experiments  of  Valentin  and  Keppler,  made  to  determine  the  exact  degree  of 
gustatory  sensibility  and  excitability. 


236  THE  CRANIAL  NERVES. 

a  disagreeable  character,  are  often  present,  and  indicate  some 
disease  of  central  origin. 

The  condition  of  gustatory  anoesthesia^  called  ''ageusia,'''' 
comprises  all  those  phenomena  which  indicate  either  a  partial 
or  complete  loss  of  the  sense  of  taste.  Thus,  the  tongue  may 
be  able  to  appreciate  certain  substances,  and  be  insensible  to 
others,  while  the  anaesthetic  condition  may  be  circumscribed 
or  diffused,  as  regards  its  anatomical  distribution,  affecting 
either  the  tip  of  the  tongue,  its  root,  or  one  or  both  sides. 
This  abnormal  state  is  observed  after  paralysis  of  the  trige- 
minus, severe  injuries  to  the  trigeminus  or  the  glosso-pharyn- 
geal  nerves,  intra-cerebral  growths  which  create  compression 
of  the  glosso-pharyngeal  or  trigeminus, '  and  atrophy  of  the 
nerves,  as  the  result  of  compression,  of  disease  of  their  in- 
herent fibers.  As  a  rule,  when  this  condition  exists,  we  shall 
find  a  similar  condition  of  the  optic,  olfactory,  trigeminus, 
pneumogastric,  spinal  accessory,  or  some  of  the  cutaneous 
branches  to  the  face. 


THE  PNEUMOGASTRIC,  OR  TENTH  NERVE. 

Owing  to  the  numerous  connections  of  the  pneumogastric 
with  other  nerves,  its  varied  and  extensive  distribution,  and 
the  important  character  of  its  functions,  this  may  properly  be 
regarded  as  one  of  the  most  remarkable  nerves  of  the  whole 
body.  It  has  been  often  known  by  the  name  of  the  ''par  ta- 
gum,^''  from  the  wandering  course  of  its  fibers,  which  are 
distributed  to  five  different  vital  organs,  viz.  :  the  heart, 
lungs,  stomach,  liver,  and  intestines,  as  well  as  to  many  other 
parts  of  secondary  importance. 

This  nerve,  like  the  seventh,  eighth,  and  ninth  nerves,  is 
considered  by  comparative  anatomists  as  belonging  to  the 

'  In  the  case  reported  by  Bottcher,  although  aguesia  existed,  the  patient  complained 
of  a  constant  burning  and  bitterness  within  the  mouth.  An  autopsy  showed  the  presence 
of  a  tumor  of  the  base  of  the  brain,  which  had  caused  atrophy  of  the  glosso-pharyngeal 
and  pneumogastric  nerves  by  a  steady  compression.  Longet  reports  cases  where  the 
nerves  passing  through  tho  jugular  foramen  were  all  more  or  less  destroyed  by  pressure 
from  a  similar  cause. 


THE  PNEUMOGA'STRIC,  OR   TENTH  NERVE.  237 

class  of  spinal  nerves,  since  it  arises  directly  and  entirely  from 
the  upper  portion  of  the  spinal  cord.  Its  superficial  point  of 
origin  lies  in  the  groove  between  the  olwary  and'  restiform 
bodies  of  the  medulla,  while  its  deep  point  of  origin  may  be 
traced  to  a  gray  nucleus  in  the  floor  of  the  fourth  ventricle, 
slightly  below  the  nucleus  for  the  glosso-pharyngeal  nerve. 

There  is  a  very  close  affiliation  between  the  deep  fibers  of 
the  pneumogastric  and  glosso-pharyngeal  nerves  within  the 


Fig.  87. — Anastomoses  of  the  pneumogastric  nerve.     (Ilirschf  eld. ) 

1,  facial  nerve;  2,  glosso-pharyngeal  nerve;  2',  anastomoses  of  the  glosso-pharyngeal 
with  the  facial;  3,  S,  pneumogastric,  loith  its  two  ganglia;  A,  4:,  spinal  accessory; 
5,  sublingual  nerve  ;  6,  superior  cervical  ganglion  of  the  sympathetic ;  7,  anastomotic 
arcade  of  the  first  two  cervical  nerves ;  8,  carotid  branch  of  the  superior  cervical 
ganglion  of  the  sympathetic;  9,  nerve  of  Jacobson ;  10,  branches  of  this  nerve  to 
the  sympathetic;  11,  branch  to  the  Eustachian  tube;  12,  branch  to  the  fenestra 
ovalis;  13,  branch  to  the  fenestra  rotunda;  14,  external  deep  petrous  nerve;  15, 
internal  deep  petrous  nerve  ;  16,  otic  ganglion  ;  17,  auricular  branch  of  the  pneumo- 
gastric ;  \S,  anastomosis  of  the  pneumogastric  with  the  spinal  accessory;  19,  anasto- 
mosis of  the  pneumogastric  with  the  sublingual;  20,  anastomosis  of  the  spinal  acces- 
sory with  the  second  pair  of  cervical  nerves;  21,  pharyngeal  plexus;  22,  superior 
laryngeal  nerve. 

substance  of  the  medulla  oblongata,  so  close  indeed  as  to  lead 
some  authors  to  consider  them  identical  with  each  other. 
These  deep  fibers  may  be  traced,  in  part,  into  the  substance 
of  the  restiform  body,  a  small  bundle  toward  the  cerebellum, 


238 


THE  CRANIAL  NERVES. 


Fig.  88, — A   diagram  showing  the   branches  of  distribution   and  communication  of  the 
pneumogastric  nerve.     Cervical  portion  of  nerve. 

1,  the  filaments  of  origin  of  the  pneumogastric  nerve;  2,  the  spinal  accessor i/ nerve  escap- 
ing from  the  medulla  oblongata,  below  the  pneumogastric  nerve ;  3,  the  upper  com- 
municating filament  between  the  pneumogastric  and  the  spinal  accessory  nerves  (often 
absent);  4,  the  '"''ganglion  of  the  root^^''  situated  in  the  jugular  foramen  ;  5,  ihc  jugu- 
lar foramai^  showing  the  transmission  of  three  nerves  ;  6,  the  communicating  filament 
between  the  pneumogastric  and  the  glosso-phari/ngeal  nerves ;  7,  the  glosso-pfiaryngeal 
nerve,  from  its  point  of  origin  to  its  escape  from  the  cavity  of  the  cranium ;  8,  the 
'"'■ganglion  of  the   tiunk''^  of   the  pneumogastric  nerve;    9,  the  loiver  filament   of 


\ 


GANGLIA    OF  THE  PNEUM0GA8TRIG  NERVE.  239 

communication  between  the  pieumogastric  and  spinal  accessory  nerves,  which  probably 
controls  the  muscles  of  the  larynx  concerned  in  phonation  and  respiration ;  10,  the 
communicating  filament  from  the  arcade,  formed  by  the  first  and  second  cervical 
nerves  ;  11,  the  communicating  filament  from  the  facial  nerve,  which  helps  to  form 
the  auricular  branch  of  the  pneumogastric  or  "Arnold's  nerve  "  ;  12,  the  three  sets  of 
filaments  which  join  the  pneumogastric  nerve  to  the  superior  cervical  ganglion  of  the 
sympathetic  system ;  13,  the  auricular  branch  of  the  pneumogastric,  or  "  Arnold's 
nerve^''  partly  formed  by  the  facial  filament  (11);  14,  the  branches  to  the  '■'■  pharyn- 
geal plexus^''  formed  also  in  part  by  the  glosso-pharyngeal ;  15,  the  supei'ior  laryngeal 
nerve,  supplying  the  mucous  lining  of  the  larynx  and  the  crico-thyroid  muscle;  16, 
the  "  depressor  nerve  of  the  heart,''''  formed  by  two  roots,  one  from  the  pneumogastric, 
and  the  other  from  the  superior  laryngeal  nerve  ;^  17,  the  inferior  or  recurrent 
laryngeal  nerve,  winding  around  an  artery  (19),  and  then  returning  to  the  larynx  to 
supply  the  muscles  of  phonation ;''  18,  the  cervical  cardiac  nerves  (sometimes  three 
in  number),  going  to  the  cardiac  plexus ;  19,  the  subclavian  artery  (if  on  the  right 
side),  and  the  arch  of  the  aorta  (if  on  the  left  side  of  the  body). 

and  a  few  toward  the  cerebrum  ;  but  the  larger  portion  pass 
to  the  median  line  of  the  floor  of  the  fourth  ventricle  or  de- 
scend into  the  substance  of  the  medulla  oblongata. 

The  pneumogastric  nerve  emerges  from  the  jugular  fora- 
men as  a  single  trunk,  but  immediately  develops  two  gan- 
glia, the  upper  of  which  is  called  the  '-'jugular  ganglion,'^'' 
or  the  "  ganglion  of  the  root^^'^  since  it  lies  close  to  and  some- 
times within  the  foramen  of  that  name.  After  the  nerve 
emerges  from  the  foramen,  another  ganglion,  about  one  quar- 
ter of  an  inch  in  length,  is  developed,  called  the  "ganglion 
of  the  trunJi^  Within  the  jugular  ganglion,  an  interchange 
of  fibers  takes  place  between  the  pneumogastric  and  spinal 
accessory  nerves  ;  and  it  seems  clear  that  the  laryngeal  and 
pharyngeal  branches  (which  are  among  the  most  decidedly 
motor  of  those  given  off  from  the  pneumogastric)  may  all,  in 
great  part,  be  traced  backward  into  the  spinal  accessory 
nerve. 

The  researches  of  Valentin,  Morganti,  Longet,  and  others 
seem  to  prove  that  the  pneumogastric  nerve  at  its  root  pos- 
sesses no  motor  power,  but  is  entirely  an  afferent  nerve,  al- 
though Stilling,  Wagner,  Muller,  Yolkman,  and  Bernard  fail 

1  For  the  physiological  effect  of  stimulation  of  this  nerve,  see  the  late  researches  of 
Cyon  and  Ludwigupon  this  nerve  in  the  rabbit;  also  text-books  of  physiology  of  Michael 
Foster,  A.  Flint,  Jr.,  and  others.  In  man,  this  nerve  is  probably  associated  with  one  of 
the  cardiac  nerves. 

2  The  filament  of  the  spinal  accessory  (No.  9  in  the  cut)  is  supposed  to  afford  to 
this  nerve  its  motor  power,  having  simply  used  the  sheath  of  the  pneumogastric  as  a 
means  of  protection  in  its  course  down  the  neck.  The  physiological  imp.ort  of  this  nerve 
shows  the  vital  necessity  for  such  protection. 


240  TEE  CRANIAL  NERVES. 

to  attribute  all  the  motor  fibers  of  this  nerve  to  either  the 
spinal  accessory  or  glosso-pharyngeal  nerves,  and  maintain 
that  motor  fibers  may  be  demonstrated  within  the  root  of  the 
pneumogastric  above  the  jugular  ganglion. 

In  regard  to  its  trunk,  there  can  be  no  doubt  that  the 
pneumogastric  is  to  be  considered  as  a  nerve  of  double  en- 
dowments, although  it  is  certain  that  these  endowments  are 
very  differently  distributed  among  its  branches.  That  it  is 
capable  of  conveying  those  impressions  which  become  sensa- 
tions when  communicated  to  the  sensorium  is  experimentally 
proved  by  the  fact  that,  when  its  trunk  is  pinched,  the  ani- 
mal gives  signs  of  acute  pain  ;  and  it  is  also  evident  from  the 
painful  consciousness  we  occasionally  have  of  any  abnormal 
condition  of  the  organs  which  it  supplies. 

BRANCHES  OF  THE  PNEUMOGASTRIC  NERVE. 

The  pneumogastric  nerve,  by  means  of  its  numerous  points 
of  distribution,  participates  in  the  operations  of  deglutition, 
phonation,  respiration,  the  circulation  of  the  hlood,  and 
the  process  of  digestion.  To  fully  describe  the  variations  in 
its  course  from  above  downward,  and  the  distribution  of  its 
branches  to  the  various  organs  (in  all  of  their  physiological 
bearings),  you  must,  of  necessity,  be  carried  into  a  discus- 
sion of  the  thoracic  and  abdominal  viscera  and  the  physio- 
logical acts  which  they  perform.  A  hasty  enumeration  of  the 
general  course  of  the  fibers  of  this  nerve  can,  therefore,  only 
be  given  here,  reserving  the  many  points  of  interest  connected 
with  it  for  other  lectures,  when  the  viscera  will  be  considered. 

The  efferent  fibers  of  the  pneumogastric  nerve  include  cer- 
tain motor  branches  which  are  distributed  into  the  pharynx, 
the  larynx,  the  oesophagus,  the  stomach,  and  the  intestinal 
canal. 

The  pharyngeal  branches  help  to  form  the  pharyngeal 
plexus  of  nerves,  and  thus  to  aid  in  the  movements  of  the 
muscles  of  that  organ  during  the  second  period  of  deglutition. ' 

'  See  lecture  upon  the  glosso-pharyngeal  nerve,  where  the  act  of  deglutition  is  fully 
discussed. 


DISTRIBUTION  OF  PNEUMOGASTRIC  NERVE.  241 

It  is  also  probable  that  these  same  muscles  tend  to  modify 
the  tone  and  quality  of  the  mice,  and  also  to  assist  in  the 


Fig.  89. — TJwracic  and  abdominal  portion  of  the  nerve. 

20,  the  thoracic  cardiac  nerves,  assisting  to  form  the  cardiac  plexus ;  21,  the  filaments  of 
communication  between  the  pneumogastric  nerve  and  the  thoracic  ganglia  of  the  sym- 
pathetic system ;  22,  the  branches  given  off  by  the  pneumogastric  nerve  to  assist  in 
forming  the  posterior  pulmonart/  plexus  ;  23,  the  branches  given  off  to  assist  in  form- 
ing the  anterior  pulmonary  plexus ;  24,  the  branches  which  form  the  oesophageal 
plexus,  and  assist  in  the  performance  of  the  ^hird  period  of  the  act  of  deglutition ; 
25,  the  gastric  branches,  supplying  the  coats  of  the  stomach  ;  26,  the  hepatic  branches, 
accompanying  the  portal  system  of  veins  ;  27,  the  intestinal  branches,  controlling,  to 
a  large  extent,  the  peristaltic  action  of  that  canal ;  28,  branches  which  can  be  traced 
to  the  kidneys,  the  spleen,  and  the  supra-renal  capsules. 


242 


THE  CRANIAL  NERVES. 


articulation  of  sounds  or  words,  although  the  lingual  muscles 
and  those  of  the  lips  are  more  directly  concerned  in  the  latter 
function. 


Fig.  90. — Distribution  of  tlic pntamvyudik.     (^llii>cliii.iu.; 

1,  trunk  of  the  left  pieumogastric  ;  2,  ganglion  of  the  trunk  ;  8,  anastomosis  with  the  spinal 
accessory ;  4,  anastomosis  with  the  sublingual ;  5,  pharyngeal  branch  (the  auricular 
branch  is  not  shown  in  the  figure)  ;  6,  superior  laryngeal  branch  ;  7,  external  laryngeal 
ncrrve ;  8,  laryngeal  plexus ;  9,  9,  inferior  laryngeal  branch;  10,  cervical  cardiac 
branch;  11,  thoracic  cardiac  branch;  12,  13,  pulmonary  branches;  14,  lingual 
branch  of  the  fifth  ;  16,  lower  portion  of  the  sublingual;  1 6,  glosso-pharyngeal ;  17, 
spinal  accessory ;  18, 19,  20,  spinal  nerves  ;  21,  phrenic  nerves ;  22,  23,  spinal  nerves ; 
24,  25,  26,  27,  28,  29,  30,  sympathetic  ganglia. 


The  laryngeal  branches  are  two  in  number,  and  are  called 
the  superior  and  inferior;  although  the  name  "  recurrent  la- 
ryngeal nerve"  is  more  often  applied  to  the  latter  on  account 


PHYSIOLOGY  OF  PNEUMOGASTRIG  NERVE.  243 

of  the  peculiarity  of  its  course,  since  it  winds  around  the  sub- 
clavian artery  before  returning  to  the  larynx,  upon  the  right 
side  of  the  body,  while  the  left  nerve  winds  around  the  arch 
of  the  aorta,  and  then  turns  backward,  to  be  distributed 
to  the  muscles  of  the  larynx.  It  is  by  means  of  these  laryn- 
geal nerves  that  the  muscles  which  move  the  xocal  cords^ 
and  thus  control  the  voice,  are  supplied  ;  while  the  same  mus- 
cles are  important  agents  in  so  adapting  the  size  of  the  open- 
ing between  the  vocal  cords,  during  inspiration,  as  to  allow 
of  an  unimpeded  entrance  of  air  to  the  lungs/  As  the  infe- 
rior nerve  is  the  one  which  supplies  all  of  the  laryngeal  mus- 
( les  but  the  crico-thyroid  and  a  portion  of  the  arytenoid,  it 
becomes  to  the  physiologist  a  nerve  of  great  importance,  since 
the  acts  of  respiration  and  phonation  are  directly  under  its 
influence.  Experiment  seems  to  have  proven,  however,  that 
the  laryngeal  nerves,  although  apparently  deriving  their  mo- 
tor power  from  the  pneumogastric,  are,  in  reality,  but  fibers 
of  the  spinal  accessory  nerve^  which  have  used  the  sheath  of 
the  pneumogastric  nerve  simply  for  protection  in  their  pas- 
sage through  the  neck.  The  spinal  accessory  nerve  is,  there- 
lore,  sometimes  called  the  "superior  respiratory  nerve  of 
]3ell,"  since  it  controls  the  movements  of  the  laryngeal  mus- 
cles during  the  act  of  inspiration  ;''  which  are  the  highest,  in 
point  of  situation,  of  any  of  the  respiratory  muscles. 

The  branches  to  the  oesophagus,  stomach,  and  intestine 
are  the  principal  agents  in  promoting  the  peristaltic  action  of 
the  alimentary  canal,  and  they  thus  aid  in  the  acts  of  degluti- 
tion and  digestion.  It  is  probable,  also,  that  the  pneumo- 
gastric nerves  are  capable  of  directly  affecting  the  secretions 
of  the  alimentary  canal,  although  the  sympathetic  system  is 

^  The  researches  of  Bernard  have  done  much  to  call  professional  attention  to  the  fact 
that  the  pneumogastric  and  spinal  nerves  are  alone  involved  in  ordinary  respiration,  but 
that,  when  it  becomes  necessary  to  bring  the  respiratory  movements  into  perfect  accord 
with  the  requirements  of  animal  life  (as  in  adapting  the  action  of  the  muscles  of  the 
larynx  to  production  of  voice),  the  spinal  accessory  nerve  becomes  an  indispensable  aid. 

2  This  statement  is  one  that  will  admit  of  question.  The  reader  is  referred  to  the 
experiments  of  Bernard  and  Bischoff  (as  given  on  a  subsequent  page)  for  the  difference 
i)ctween  the  effect  of  the  spinal  accessory  fibers  upon  the  glottis  from  those  of  the  pneu- 
mogastric itself. 


2U 


THE  CRANIAL  NERVES. 


still  regarded  as  the  means  by  which  these  nerves  exert  their 
influence  upon  that  portion  of  the  body. 


Fig.  91. — Nei'ves  of  the  larynx, posterior  Fig.  92. — Nerccs  of  the  larynx,  lateral 

vieio.     (After  Sappey.)  view.     (After  Hirschfeld.) 

Fig.  91. — 1, 1,  superior  laryngeal  nerves  passing  through  the  thyro-hyoid  membrane ;  2,  J 
external  laryngeal  branch  supplying  the  crico-thyroid  muscle;  3,  ascending  brancht- 
distributed  to  the  mucous  membrane  of  the  tongue  ;  4,  transverse  branches  distribu- 
ted to  the  mucous  membrane  of  the  epiglottis  and  the  aryteno-epiglottidean  folds  ;  5, 
descending  branches  passing  to  the  mucous  membrane  covering  the  posterior  surfac<' 
of  the  larynx  (two  of  these,  of  considerable  size,  cross  the  arjrtenoid  muscle  to  suppl> 
the  mucous  membrane  lining  the  walls  of  the  vestibule);  6,  branch  connecting  tin 
superior  with  the  inferior  laryngeal  nerve ;  Y,  the  same  branch  divided  near  its  point 
of  origin ;  8,  8,  inferior  laryngeal  nerve ;  9,  branch  to  the  posterior  crico-arytenoid 
muscle,  which  is  here  divided  in  order  to  show  the  next  nerve ;  10,  branch  to  the 
arytenoid  winding  under  the  lower  border  of  the  muscle  so  as  to  enter  it  from  its 
inner  surface;  11,  branch  to  the  lateral  crico-arytenoid  muscle;  12,  branch  to  the 
thyro-arytenoid  muscle. 

Fig.  92. — a,  section  of  the  hyoid  bone ;  6,  section  of  the  thyroid  cartilage ;  c,  thyro-hyoid 
membrane ;  d,  cricoid  cartilage ;  e,  trachea  ;  /,  oesophagus ;  g,  epiglottis  ;  /t,  superior 
cornu  of  the  thyroid  cartilage  ;  «',  great  cornu  of  the  hyoid  bone ;  k,  lateral  thyro-hyoid 
ligament ;  /,  thyro-hyoid  membrane ;  m,  posterior  crico-arytenoid  muscle  ;  n,  lateral 
crico-arytenoid  muscle ;  o,  thyro-arytenoid  muscle ;  /),  base  of  the  tongue ;  1,  recur- 
rent laryngeal  nerve ;  2,  branches  given  off  from  this  nerve  to  the  posterior  crico- 
arytenoid muscle ;  3,  branch  to  the  lateral  crico-arytenoid  muscle ;  4,  branch  to  tin 
thyro-arytenoid  muscle ;  5,  branch  to  the  aiytenoid  muscle ;  6,  right  superior  laryn- 
geal nerve ;  7,  anastomosis  of  this  nerve  with  the  inferior  laryngeal ;  8,  descending 
branches  from  the  superior  laryngeal ;  9,  middle  branches  of  the  same  nerve ;  10, 
ascending  branches. 

In  addition  to  the  branches,  which  are  considered  as  of  the 
greatest  physiological  importance,  certain  other  motor  fibers 


I 


PHYSIOLOGY  OF  PNEUMOGASTRIC  NERVE. 


245 


are  now  traced  with  tolerable  certainty  to  the  trunk  of  the 
pneumogastric  nerve,  which  are  not  unimportant.  Thus  we 
may  include  certain  nerves  which  supply  the  plain  muscular 
fibers  of  the  trachea  and  of  the  larger  bronchial  tubes,  fibers 
which  exert  a  vaso -motor ial  influence  upon  the  blood-vessels 
of  the  lungs,  an  inJiihitory  nerve  for  the  heart,  and  certain 
libers  which  are  distributed  to 
the  lungs  and  the  heart,  which 
are  supposed  to  exert  a  trophic 
influence. 

The  properties  and  functions 
of  the  cardiac  nerve,  and  in 
what  way  the  pneumogastric 
nerve  influences  the  action  of 
the  heart,  are  physiological 
questions  of  the  greatest  impor- 
tance. It  is  now  known  that 
section  of  the  pneumogastric  in 
the  neck,  instead  of  arresting 
the  action  of  the  heart,  in- 
creases the  frequency  of  its 
contractions ;  while  galvanism 
of  the  divided  ends  causes  the 
heart's  action  to  stop  during  its 
diastole,  if  the  current  be  a 
powerful  one,  and,  if  a  weak 
one,  the  heart's  action  is  propor- 
tionately slowed. 

The  depressor  nerve  of  the 
Jieart  is  shown,'  in  the  diagram- 
matic representation  of  the  pneu- 
mogastric nerve  and  its  branches,  to  arise  from  two  filaments, 
derived,  respectively,  from  the  pneumogastric  and  the  superior 
laryngeal  nerves.     The  importance  of  this  nerve  in  explaining 

'  For  the  method  of  origin  of  this  nerve,  see  the  diagrammatic  plate  of  the  upper 
half  of  the  pneumogastric  nerve,  page  238.  While  the  diagram  illustrates  the  construc- 
tion of  this  nerve,  as  found  in  the  rabbit  by  Cyon,  it  is  still  questionable  whether  a  simi- 
lar method  of  origin  can  be  demonstrated  in  man.  That  the  nerve  exists  is  not  a  matter 
of  doubt ;  but  it  is  impossible  to  positively  state  its  method  of  origin  or  its  precise  course. 
18 


Fig.  93. — Branches  of  the  pneumogastric 
to  the  heart.     (Bernard.) 

C,  heart ;  a,  carotid  artery  going  to  the 
brain ;  w,  branches  of  the  pneumo- 
gastric going  to  the  heart. 


246  THE  CRANIAL  NERVES. 

many  physiological  effects  of  galvanism  of  the  pneumogastric 
has  been  developed  through  the  efforts  of  Cyon  and  Ludwig, 
in  their  prize  essay  of  1867,  who  showed  to  the  profession  its 
power  of  decreasing  the  beats  of  the  heart,  and  who  thus 
afforded  the  means  of  satisfactorily  explaining  many  phe- 
nomena met  with  in  the  daily  practice  of  medicine.  If  the 
abdomen  of  a  frog  be  exposed,  and  the  intestine  struck  sharp- 
ly, the  heart  will  be  seen  to  stand  still,  as  if  the  depressor 
nerve  of  the  heart  had  been  galvanized  ;  while  stimulation 
of  the  mesenteric  nerves,  before  they  join  the  sympathetic 
chain,  will  have  a  like  result.  It  has  been  found  that  the 
irritation  of  an  inflamed  peritoneal  surface,  even  if  gently 
practiced,  will  decrease  the  heart  pulsations,  and  that  severe 
shock  or  nery  intense  pain^  no  matter  where  it  arises^  wiU 
also  have  the  same  effect  upon  the  heart. 

Such  evidences  of  reflex  action  are  apparently  transmitted 
through  these  depressor  nerves  of  the  heart  alone,  and  they 
help  us  to  explain  why  pain  may  create,  in  the  human  race, 
attacks  of  fainting,  and  why  some  types  of  inflammatory  dis- 
eases and  states  of  collapse  and  shock  are  associated  with  a 
decrease  in  the  pulsations  of  the  heart.  The  action  of  atropin^ 
even  in  small  doses,  seems  to  entirely  arrest  the  influence  of 
this  nerve  upon  the  heart,  and  a  guide  to  the  administration 
of  this  drug  may  thus  be  derived  from  physiology,  while 
the  effects  thereof  may,  in  some  instances,  be  thus  made 
clear. 

The  cardiac  nerves  of  the  pneumogastric  are  undoubtedly 
connected  with  the  other  nerves  of  the  cardiac  ganglia^"^  and 
act  upon  the  heart  fibers  indirectly,  rather  than  directly,  with- 
out the  intervention  of  the  ganglion.  It  has  lately  been  proven 
that  certain  other  cardiac  nerves^  whose  function  is  accelera- 
tory,  rather  than  depressing,  to  the  heart,  cau  be  traced  to  the 
cervical  portion  of  the  spinal  cord  as  their  point  of  origin, 
but  they  have  no  connection  with  the  pneumogastric  nerve. 

'  The  vasomotor  nerves  of  the  lung  are  derived,  according  to  Franck,  from  the  upper 
cervical  ganglia  of  the  sympathetic,  their  primary  origin,  however,  being  in  the  ccrvico- 
dorsal  region  of  the  cord. 


PHYSIOLOGY  OF  PNEUMOGASTRIG  NERVE.  247 

The  afferent  fibers  of  the  pneumogastric  nerve,  or  those 
which  carry  impressions  from  the  periphery  of  the  nerve  to- 
ward its  point  of  origin,  comprise  the  sensory  filaments '  dis- 
tributed to  the  entire  respiratory  tract ;  and  also  those  sensory 
nerves  which  supply  the  pharynx,  the  oesophagus,  and  the 
stomach  ;  fibers  which  assist  to  produce  the  secretion  of  the 
saliva ;  fibers  which  tend  to  arrest  the  secretion  of  the  pan- 
creas ;  a  special  inhibitory  nerve  upon  the  vaso-motor  center 
of  the  medulla  oblongata  ;  and,  finally,  a  special  set  of  fibers 
which  both  augment  and  retard,  at  will,  the  action  of  the 
respiratory  center  of  the  medulla  oblongata. 

As  the  pneumogastric  nerve  is  more  apparently,  although 
perhaps  not  more  importantly,  connected  with  the  act  of  respi- 
ration^ we  will  first  consider  the  two  sets  of  fibers  which  have 
been  mentioned  above  as  influencing  the  action  of  the  respira- 
tory center.  It  has  been  shown  by  Rosenthal  that  the  supe- 
rior laryngeal  nerve,  when  stimulated  by  a  galvanic  current, 
decreases  the  number  of  respirations,  while  the  main  trunk 
of  the  pneumogastric  nerve,  when  similarly  stimulated,  tends 
to  increase  the  number  of  respirations.  Thus,  the  fact  that 
the  vagus  nerve  possessed  two  sets  of  respiratory  fibers^  an 
acceleratory  and  an  inhibitory,  seems  to  be  well  established, 
although  some  observers  have  not,  as  yet,  admitted  the  posi- 
tiveness  of  the  experiment. 

As  regards  those  branches  of  the  pneumogastric  which 
seem  to  exert  a  specific  infiuence  upon  the  various  secretions 
of  the  alimentary  canal,  we  have  yet  much  to  learn.  As  a 
general  rule,  it  may  be  stated  that  anything  which  tends  to 
create  an  increased  activity  in  the  epithelial  cells,  rather  than 
in  the  blood  supply  of  the  part,  tends  also  to  increase  the  se- 
cretion.    Thus  a  drug  may  excite  any  special  secretion,  first, 

'  Sommerbrodt  ("  Centralbl.  f.  d.  med.  Wiss.,"  December,  1880)  points  out  a  mechan- 
ism of  compensation  by  which  the  action  of  the  lungs  and  of  the  heart  is  coordinated. 
Thus,  a  rise  in  the  intra-bronchial  pressure  (as  occurs  in  singing,  crying,  coughing,  etc.), 
by  irritating  the  sensory  nerves  of  the  lungs,  excites  a  reflex  depressing  action  on  the 
vaso-motor  and  cardio-inhibitory  nerves.  The  resulting  vascular  dilatation  and  accelera- 
tion of  the  heart's  action  react  upon  the  lung  in  two  ways.  They  prevent  the  natural  ten- 
dency to  stasis  of  the  blood  in  the  bronchial  walls,  and  they  insure  the  rapid  renewal  of 
oxygen,  demanded  by  the  increase  in  pulmonary  activity. 


248  THE  CRANIAL  NERVES. 

by  acting  upon  the  nerve  center  which  controls  that  part ; 
secondly,  by  a  reflex  act  through  the  nerves  of  the  part ; 
thirdly,  by  acting  as  a  direct  chemical  stimulus  to  the  cells  ; 
and,  fourthly,  by  increasing  the  amount  of  blood  in  the 
part,  through  dilatation  of  the  blood-vessels. 

That  an  iuMMtory  effect  upon  the  vaso-motor  center  of  the 
medulla  is  possessed  by  some  of  the  fibers  of  the  pneumogas- 
tric  nerve,  is  proven  by  the  effect  of  galvanism  of  the  vagus 
upon  blood  pressure  ;  since,  when  the  depressor  nerve  of  the 
heart  is  divided  and  the  end  connected  with  the  brain  is  gal- 
vanized, the  blood  pressure  falls,  although  the  heart  is  not 
affected,  as  it  would  be  if  the  cardiac  portion  of  the  nerve 
were  stimulated. 

COURSE   OF  THE   PNEUMOGASTRIC   NERVE   OF  THE   TWO   SIDES. 

The  important  functions  of  the  vagus  render  it  necessary 
that  every  precaution  shall  be  taken  by  Nature  to  prevent  its 
possible  injury,  especially  during  its  passage  through  the 
neck  ;  since,  within  the  thorax  and  the  cavity  of  the  abdomen, 
the  viscera  and  the  bony  encasements  tend  to  render  all  possi- 
ble dangers  of  injury  a  minimum.  We  therefore  find  this 
nerve  inclosed  within  the  sheath  of  the  carotid  artery,  where 
it  is  placed  between  the  artery  and  the  internal  jugular  vein, 
lying  also  posteriorly  to  them  both.  By  this  provision  the 
nerve  is  placed  between  fluid  upon  either  side,  and  thus  all 
danger  of  transmitted  force  affecting  it  is  obviated,  while  the 
deep  situation  of  the  carotid  and  the  close  proximity  of  the 
transverse  processes  of  the  cervical  vertebrae  make  the  nerve 
secure  from  the  danger  of  wounds  of  pointed  instruments.  It 
is  almost  an  impossibility,  therefore,  for  this  nerve  to  become 
involved  in  any  form  of  accident,  without  the  large  vessels  of 
the  neck  being  simultaneously  injured  and  the  patient  sacri- 
ficed. 

Even  in  the  jugular  foramen  the  nerve  is  wrapped  in  the 
same  sheath  as  the  spinal  accessory  nerve,  and  it  is  placed 
behind  both  the  glosso-pharyngeal  nerve  and  the  jugular 
vein ;  while,  to  reach  the  commencement  of  the  common  ca- 


SECTION  OF  PNEUM0GA8TRIC  NERVE.  249 

rotid  artery,  the  nerve  is  placed  in  close  relation  to  the  inter- 
nal carotid  artery  and  the  jugular  vein. 

As  the  nerves  of  either  side  reach  the  lower  portion  of  the 
neck,  each  takes  a  different  course.  The  right  nerve  passes 
between  the  subclavian  artery  and  vein,  then  along  the  side 
of  the  trachea,  then  to  the  back  of  the  root  of  the  lung,  then 
along  the  side  of  the  oesophagus  as  two  cords,  then  as  a  single 
cord  along  the  back  of  that  tube  through  the  oesophageal 
opening  of  the  diaphragm,  and  terminates  in  the  solar  and 
splenic  plexuses,  after  giving  off  branches  to  the  posterior 
surface  of  the  stomach,  and  some  filaments  to  the  liver.  The 
left  nerve  passes  between  the  left  common  carotid  and  left 
subclavian  arteries  and  behind  the  left  innominate  vein,  then 
arches  across  the  aorta  and  passes  to  the  back  of  the  root  of 
the  lung,  then  as  two  cords  along  the  sides  of  the  oesophagus, 
where  it  joins  with  its  fellow  to  form  the  oesophageal  plexus, 
then,  as  a  single  cord,  in  front  of  the  oesophagus  through  the 
oesophageal  opening  of  the  diaphragm,  when  it  supplies  the 
anterior  surface  of  the  stomach  and  probably  terminates  in 
the  hepatic  plexus. 

THE   EFFECTS   OF   SECTION   OF   THE    PNEUMOGASTBIC   NERVE. 

The  effects  of  section  of  both  of  the  pneumogastric  trunks,' 
if  made  below  the  jugular  ganglion,  are  most  markedly  ex- 
hibited in  the  larynx,  the  lungs,  and  the  heart. 

Effects  upon  the  Larynx.— The  larynx  becomes  impaired 
in  its  function,  and  the  glottis  remains  partially  closed  by  the 
vocal  cords,  whose  abductor  muscles  are  now  paralyzed,  thus 
impeding  the  free  entrance  of  air  into  the  lung ;  and,  as  a 
consequence  of  this,  the  respirations  are,  for  a  short  time, 
hurried  and  difficult,  although  they  soon  become  diminished 
in  frequency.'    The  inspiratory  effort  becomes  unusually 

*  Animals  usually  survive  after  one  vagus  nerve  is  divided,  and  present  only  a  hoarse- 
ness of  voice  ;  an  increased  frequency  of  respiration,  emphysema,  or  pulmonary  congestion 
may  be  a  sequel  to  the  operation.  Union  of  the  divided  nerve  has  been  observed  in 
numerous  instances. 

2  Were  it  not  for  the  nerves  of  the  skin,  and  other  sensory  nerves  which  can  transmit 
the  feeling  of  pain,  and  which  also  possess  the  power  of  exciting  respiratory  efforts,  sec- 
tion of  both  vagi  ought,  theoretically,  to  stop  respiration  at  once. 


250  THE  CRANIAL  NERVES. 

slotv,  while  expiration  is  remarkably  rapid  and  sometimes 
audible  ;  tlie  intercostal  spaces  sink  inward  during  the  eleva- 
tion of  the  ribs,  showing  that  the  lungs  are  not  fully  inflated 
with  air,  and  death  occurs  in  from  one  to  six  days,  as  the 
result  of  pulmonary  consolidation.  There  are  no  symptoms 
accompanying  the  approach  of  death,  except  a  gradual  fail- 
ure of  respiration  and  a  peculiar  sluggishness,'  which  is  char- 
acteristic and  probably  dependent  upon  carbonic-acid  poi- 
soning. 

The  immediate  cause  of  death  can  undoubtedly  be  attri- 
buted to  the  altered  condition  of  the  lungs,  which  present  a 
state  of  simple  vascular  engorgement,  without  any  apparent 
inflammatory  condition  either  of  the  lung  or  pleura.  In  very 
young  animals,  the  division  of  the  vagi  is  followed  by  almost 
immediate  death,  but  this  is  attributable  rather  to  paralysis 
of  the  glottis  and  the  ensuing  suffocation  than  to  pulmonary 
congestion,  which  requires  time  for  its  development. 

Effects  upon  the  Lungs. — There  have  been  many  theories 
advanced  to  explain  the  effects  of  division  of  the  pneumo- 
gastric  nerves  upon  the  lung  tissue,  and  particularly  to  ex- 
plain why  such  an  operative  procedure  should  be  followed  by 
excessive  pulmonary  hypersemia,  so  as  to  cause  the  specific 
gravity  of  the  lungs  to  exceed  that  of  water.  It  seems  to  me 
that  the  theory,  that  the  entrance  of  secretions  or  food  into 
the  lung  through  the  paralyzed  glottis  (which  can  no  longer 
spontaneously  expel  any  foreign  body)  will  explain  the  con- 
solidation of  the  lung  as  a  direct  result  of  irritation,  is  not  sus- 
tained either  by  the  pathology  of  the  pulmonary  lesion  or  by 
experiments  where  a  canula  has  been  placed  in  the  larynx  to 
prevent  this  cause  of  irritation.  Bernard  has  explained  it  on 
the  ground  that  traumatic  emphysema  of  the  lung  is  devel- 
oped from  the  labored  inspiratory  efforts  made  by  the  animal 
after  the  division  of  the  vagi,  thus  creating  a  mechanical 
hcemorrhage  which  eventually  consolidates  the  lung  tissue. 
He  sustains  this  theory  by  the  fact  that  birds,  whose  lungs 
are  fixed  and  immovable,  and  are  therefore  inexpansible,  fail 

'  The  convulsions  which  often  accompany  asphyxia  are  usually  absent  in  these  animals. 


EFFECTS  OF  SECTION  OF  PNEUMO  GASTRIC.  251 

to  present  this  condition  when  the  vagi  are  divided,  although 
death  is  produced. 

To  my  mind,  the  most  plausible  explanation  of  the  effects 
of  this  operation  upon  the  lungs  may  be  regarded  as  a  purely 
mechanical  one,  dependent  upon  the  impeded  entrance  of 
air  through  the  larynx.  During  each  inspiratory  effort,  the 
depression  of  the  diaphragm  and  the  elevation  of  the  ribs 
tend  to  create  a  vacuum  within  the  pleural  and  pericardial 
sacs,  and  thus  favor  the  entrance  of  both  air  and  blood  into 
the  thorax.  So  long  as  the  entrance  of  either  one  remains 
unimpeded,  the  proper  balance  between  the  two  is  preserved, 
and  neither  too  much  air  nor  too  much  blood  is  sucked  in  with 
each  inspiration ;  but,  when  the  air  is  prevented  from  enter- 
ing, an  excess  of  blood  flows  into  the  lung  with  each  inspira- 
tion, and,  in  the  course  of  time,  the  lung  is  thus  mechanically 
consolidated.  Were  the  number  of  respirations  not  greatly 
decreased  from  the  normal  standard,  the  duration  of  life 
would  probably  be  proportionally  shortened,  as  the  same 
effect  would  be  produced  in  shorter  time.  The  death  of  birds 
and  some  other  animals,  after  section  of  the  vagi,  may  possi- 
bly be  explained  on  the  ground  of  a  too  powerful  impression 
upon  the  respiratory  center. 

Effects  upon  the  Heart. — In  addition  to  the  effects  upon 
the  lungs,  division  of  the  pneumogastric  nerves  is  followed  by 
a  marked  alteration  of  the  action  of  the  heart.  The  effects 
are  somewhat  similar  to  those  which  might  result  if  the  gov- 
ernor of  a  steam-engine  were  suddenly  removed,  and  the 
piece  of  mechanism  allowed  to  proceed  without  its  control- 
ling influence.  Thus  the  heart  increases  slightly  in  the  rapid- 
ity of  its  pulsations,  and  the  amount  of  cardiac  pressure 
becomes  slightly  diminished,  when  one  of  the  nerves  is  sev- 
ered ;  but,  when  both  are  divided,  the  respiratory  symptoms 
far  outweigh  those  of  the  heart,  but  its  action  is  still  accel- 
erated and  often  irregular,  since  the  inhibitory  power  of  the 
nerves  is  destroyed. 

Effects  upon  the  Digestive  Tract.  —  The  oesophageal 
branches  of  the  vagus  are  the  motor  nerves,  which  control  the 


252  THE  CRANIAL  NERVES. 

peristaltic  action  of  that  tube  (as  is  proven  by  the  fact  that 
division  of  the  pneumogastric  nerves  of  both  sides  causes 
complete  paralysis),  and  also  the  means  by  which  sensation 
is  afforded  to  its  mucous  lining.  In  animals  which  have 
been  subjected  to  division  of  the  vagi,  attempts  to  swallow 
food  in  any  considerable  quantities  create  a  distention  of 
the  upper  part  of  the  oesophagus,  and  regurgitation  by  means 
of  the  mouth  takes  place  without  the  food  entering  the 
stomach,'  as  was  proven  by  Bernard,  who  made  a  gastric 
fistula  in  a  dog  before  dividing  the  pneumogastrics,  in  order 
to  decide  this  point.  From  what  source  the  motor  fibers 
which  control  the  movements  of  the  oesophagus  are  derived 
by  the  pneumogastric  nerve  is  still  a  matter  of  doubt ;  the 
root  of  the  nerve  itseK  seems  to  possess  some  influence  upon 
it,  thus  showing  that  it  can  not  be  traced  to  the  nerves  which 
communicate  with  it  below  the  jugular  foramen. 

The  branches  which  are  distributed  to  the  liver  by  the 
pneumogastric  nerves  are  probably,  in  some  way,  connected 
with  the  glycogenic  function  of  that  organ,  since  division  of 
these  nerves  causes  the  liver  to  yield  no  traces  of  sugar  after 
the  animal  succumbs,  which  is  contrary  to  the  result  obtained 
after  death  in  animals  which  have  these  nerves  intact.  When 
the  nerves  are  divided  in  the  living  animal,  and  the  end  near- 
est to  the  brain  is  galvanized,  an  increase  of  sugar  in  the 
blood  is  thus  artificially  produced  at  any  time  during  the  life 
of  the  animal,  and  traces  of  the  same  may  also  be  found  in 
the  urine.  A  similar  hyper-secretion  of  sugar  by  the  liver 
may  be  also  noticed  after  the  inhalation  of  irritating  vapors 
or  anaesthetics,  probably  through  the  influence  of  the  vagi. 

The  gastric  branches  of  the  pneumogastrics  show  a  marked 
alteration  in  their  power  of  control  over  that  organ  when  the 
main  nerve  trunks  are  divided.  The  mucous  lining  of  the 
stomach  becomes  at  once  pale,  and  the  secretion  of  gastric 
juice  apparently  arrested,  although  a  slight  amount  of  se- 
cretion may  return  in  a  few  days  if  the  animal  survive.     The 

'  Physiologists  are  not  agi'eed  as  to  the  seat  of  the  reflex  act  of  vomiting  which  fol- 
lows division  of  the  vagi. 


CLINICAL  RELATIONS  OF  PNEUMOQASTRIG.  253 

sensations  of  hunger  and  thirst  remain,  but  are  sensibly  di- 
minished.  Absorption  by  the  stomach  is  evidently  delayed, 
but  not  arrested,  as  has  been  proven  by  the  introduction  of 
poisons  into  that  organ. 

The  intestinal  branches  of  the  vagi  unquestionably  con- 
trol the  secretions  of  the  canal,  and  section  of  the  nerves 
has  been  shown  to  prevent  the  action  of  the  most  powerful 
cathartics,  even  in  fatal  doses,  when  administered  immedi- 
ately before  the  vagi  were  divided.  It  is  still  a  question 
whether  the  pneumogastric  nerves  influence  the  secretions  of 
the  intestinal  canal  directly,  or  through  the  sympathetic  sys- 
tem by  means  of  communicating  filaments. 

If  the  latter  be  the  case,  those  filaments  of  communication 
which  control  the  stomach  and  oesophagus  must  be  sought  for 
high  up  in  the  cervical  region. 

CLII^ICAL   POII^TS   PERTAINING   TO   THE   PNEUMOGASTRIC   NERVE. 

The  physiological  function  of  the  separate  branches  of  the 
pneumogastric,  as  mentioned  in  preceding  pages,  will  assist 
you  in  appreciating  the  various  manifestations  of  diseased 
conditions  of  the  main  trunk  of  the  vagus,  or  of  its  individual 
branches.  You  can  understand,  from  what  has  previously 
been  said,  that  the  effect  of  degeneration,  section,  or  pressure 
upon  this  important  nerve  must  vary  with  the  seat  of  the 
lesion ;  since  those  branches  given  off  above  the  point  where 
the  nerve  is  impaired  will  manifest  their  usual  powers,  while 
those  given  off  below  that  point  wiU  show  symptoms  of  par- 
tial or  complete  paralysis.  We  can,  therefore,  study  the  effects 
of  impairment  of  the  pneumogastric  nerve  by  considering  the 
individual  branches  in  their  order  from  above  downward,  and 
recording  the  special  types  of  disease  which  are  liable  to  cre- 
ate symptoms  referable  to  each  branch. 

The  pharyngeal  branch  contains  both  motor  and  sensory 
fibers  ;  hence  injury  to  its  structure  will  create  both  paralysis 
and  anaesthesia,  while  simple  irritation  of  its  fibers  will  tend 
to  create  contraction  or  spasm  of  certain  muscles  to  which 
its  motor  fibers  are  distributed.     We  thus  see,  in  attacks  of 


254  THE  CRANIAL  NERVES. 

hysteria,  the  so-called  "globus  hystericus^'''  a  spasmodic 
affection  of  the  pharynx,  due  to  some  irritation  of  the 
pneumogastric  trunk  or  of  the  pharyngeal  branches.  We 
also  occasionally  meet  true  paralysis  of  this  branch ;  in 
which  case,  the  act  of  deglutition  is  greatly  impaired,  and, 
if  the  disease  is  bilateral,  swallowing  is  rendered  almost  an 
impossibility. 

The  superior  laryngeal  branchy  whose  function  is  to  sup- 
ply the  mucous  lining  of  the  larynx  with  sensibility, '  becomes, 
under  irritation,  the  cause  of  ''spasm  of  the  glottis"  and 
of  ''whooping-cough."  The  former  condition,  called  also 
'' stridulous  Zar2/7^<7^Y^5"  and  "Kopp's  asthma,"  is  a  disease 
peculiar  to  children,  which  tends  toward  asphyxia,  but  which 
is  rarely  if  ever  fatal.  It  usually  occurs  during  the  night, 
and  seems  to  affect  children  who  have  been  in  apparent  health. 
It  is  most  common  during  the  cold  months  ;  is  sometimes  as- 
sociated with  convulsions  ;  and  is  characterized  by  a  sibilant 
character  to  the  respiration,  pallor,  or  turgidity  of  the  coun- 
tenance, and  a  peculiar  retraction  of  the  head.  In  rare  cases, 
this  condition  is  met  with  in  the  adult,  during  attacks  of  hys- 
teria. It  seems  to  be  dependent,  in  children,  upon  dentition, 
digestive  irritation,  anaemia,  rickets,  etc. 

The  experiments  of  Rosenthal  seem  to  point  to  the  superior 
laryngeal  nerve  as  the  exciting  cause  of  the  convulsive  cough 
of  "pertussis^^^  and  also  of  that  analogous  cough  often  met 
with  in  hysterical  subjects,  since  artificial  stimulation  of  the 
nerve  produced,  with  this  observer,  similar  results.  Whether 
the  irritation  of  the  nerve  proceeds  from  the  catarrhal  in- 
flammation which  exists  in  the  respiratory  passages,  or  irri- 
tation of  some  spinal  or  cerebral  center,  is  not  yet  well  deter- 
mined. 

The  recurrent  laryngeal  branch  is  of  great  clinical  impor- 
tance, since  its  peculiar  course  often  makes  it  a  guide  to  aneu- 
rism of  the  large  blood-vessels  by  the  peculiar  symptoms  which 

'  See  page  232  of  this  volume. 

^  The  reader  is  referred  to  "A  Treatise  on  Surgical  Diagnosis"  (Xew  York,  1881),  by 
the  author,  for  all  the  points  of  diagnosis  of  this  type  of  disease. 


CLimCAL  RELATIONS  OF  PNEUMOGASTRIG.  255 

it  creates  within  the  larynx.'  The  so-called  "brassy  cough" 
is,  by  some  surgeons,  considered  as  pathognomonic  of  press- 
ure upon  or  irritation  of  this  branch,  and  strongly  indicative 
of  aneurism  of  the  subclavian,  carotids,  the  arteria  innomi- 
nata,  or  of  the  left  side  of  the  arch  of  the  aorta. 

This  branch  may  be  affected  by  central  causes,  as  well  as 
by  peripheral  pressure  or  irritation.  As  examples  of  the  cen- 
tral causes  of  impairment  of  this  nerve  may  be  mentioned 
those  cases  of  apoplexy,  cerebral  tumors,  hysteria,  diphthe- 
ria, typhoid  fever,  and  reflex  irritation  from  diseases  of  the 
uterus  or  genitals,  where  the  larynx  is  markedly  affected. 
The  peripheral  causes  which  more  commonly  affect  the  recur- 
rent laryngeal  nerve,  include  catarrhal,  tuberculous,  and 
syphilitic  inflammations  of  the  larynx,  traumatism,  the  press- 
ure of  growing  tumors,  as  aneurism,  goitre,  sarcoma,  cancer, 
lymphatic  tumors,  tumors  of  the  oesophagus,  etc. 

The  experiments  of  Bernard,  Bischoff,  and  Waller '  (given 
in  some  detail  in  previous  pages)  will  help  to  explain  how  a 
lesion,  which  excites  laryngeal  symptoms,  may  occasionally 
be  situated  away  from  the  line  of  the  pneumogastric  nerve, 
since  the  spinal  accessory  nerve  may  be  the  seat  of  irritation 
or  degeneration.  They  will  also  help  to  explain  why  the  ef- 
fects of  bilateral  paralysis  of  the  recurrent  branch  do  not 
produce  dyspnoea,  at  the  same  time  that  it  causes  the  voice 
to  be  lost ;  why  the  vocal  cords  are  seen  to  be  cadaveric  and 
relaxed  ;  and  why  the  act  of  coughing  and  the  expulsion  of 
laryngeal  mucus  is  no  longer  possible. 

The  pulmonary  'branches  of  the  nerve  are  unquestionably 
concerned,  to  some  extent,  in  the  conditions  associated  with 
bronchial  spasm,  since  asthma  may  be  developed  by  mental 
influences  acting  upon  the  origin  of  the  vagus.  Moreover,  we 
often  see  severe  types  of  this  disease  produced  by  the  press- 
ure of  thoracic  tumors  upon  the  pneumogastric ;  by  the  in- 
halation of  substances  possessing  slight  irritative  qualities; 
by  uterine  irritation,  acting  as  a  cause  of  reflex  action  through 
the  pneumogastric  nerve ;   and  by  fright,  shock,  exposure, 

^  See  page  264. 


256  THE  CRANIAL  NERVES. 

etc.     The  symptoms  of  asthma  are  too  well  known  to  be  hei< 
repeated. 

We  have  one  other  condition  developed  as  the  effect  of 
pressure  upon,  or  destruction  of,  the  vagus,  viz.,  paralysis  of 
the  pulmonary  branches  and  the  consequent  paralytic  condi- 
tion of  the  blood-vessels  of  the  lung.  It  is  to  this  condition 
that  some  authors  attempt  to  refer  the  serous  infiltration 
into  the  parenchyma  of  the  lung  which  follows  section  of  this 
nerve ; '  and  we  know,  clinically,  that  a  similar  condition  is 
sometimes  produced  by  compression  of  the  nerve  by  a  tuber- 
culous or  cancerous  degeneration  of  the  lymphatic  glands, 
especially  those  situated  near  to  the  bifurcation  of  the  trachea, 
and  by  aneurism  of  the  thoracic  vessels.  The  same  condition 
has  been  observed  after  injuries  to  the  organs  of  the  chest, 
and  from  the  section  of  some  of  the  branches  of  the  vagus, 
during  an  attempt  to  ligate  the  subclavian  in  its  first  portion 
or  the  arteria  innominata. 

The  cardiac  branches  seem  to  exert  a  more  marked  effect 
upon  the  heart  when  exposed  to  irritation  than  when  actu- 
ally destroyed  by  degeneration  or  section.  An  artificial 
*' angina  pectoris"  may  be  produced  by  pressure  upon  the 
vagus  in  the  neck  (as  performed  by  Czermak  upon  himself), 
and  the  heart's  action  may  thus  be  almost  entirely  arrested. 
It  may  be  stated,  I  think,  that  angina  pectoris,  sometimes 
called  "cardiac  neuralgia,"'  is  one  of  those  neuroses  of  the 
heart  which  depend,  to  a  large  extent,  upon  changes  of  a 
secondary  character  in  the  terminal  filaments  of  the  vagus  or 
the  cardiac  ganglia. 

The  symptoms  of  this  affection  are  very  distressing  to  the 
patient,  and  often  fatal.  The  attack  usually  begins  with  a 
sense  of  extreme  constriction  within  the  chest,  which  is  fol- 
lowed by  radiating  pains  of  a  very  intense  character,  which 

'  For  the  different  theories  advanced  to  explain  this  effect,  the  reader  is  referred  to 
page  250  of  this  volume. 

^  I  prefer  to  limit  the  term  "  angina  pectoris  "  to  those  cases  only  where  the  exciting 
causes  have  resulted  in  defective  heart  power,  and  to  apply  the  term  "  cardiac  neuralgia  " 
to  those  cases  where  the  power  of  the  heart  is  normal.  This  I  consider  to  be  the  true 
pathological  distinction. 


GARDIALGIA,  BOULIMIA,  POLYDIPSIA.  257 

shoot  down  the  arm  or  into  the  neck.  The  paroxysms  pro- 
duce the  most  rapid  exhaustion,  and  are  not  usually  long 
continued.  The  various  pathological  conditions  found  to 
exist  in  this  affection  include  an  ossified  state  of  the  coro- 
nary vessels  (thus  interfering  with  the  nutrition  of  the  heart 
walls) ;  cardiac  hypertrophy  (which  is  usually  of  that  form 
called  compensatory,  since  the  cavities  of  the  heart  are  gen- 
erally dilated) ;  fatty  degeneration  of  the  heart ;  valvular 
lesions  (with  their  secondary  changes  in  the  size  of  the  cavi- 
ties) ;  and  aneurism  within  the  pericardial  sac. 

The  gastric  branches  of  the  vagus  are  associated  with  the 
conditions  of  gastrodynia  (cardialgia),  boulimia,  polydipsia, 
nervous  vomiting,  and  disorders  of  the  secretory  follicles  of 
the  organ,  as  well  as  its  power  of  absorption.  Gastrodynia  is 
a  paroxysmal  attack  of  neuralgia  of  the  sensory  fibers  of  the 
stomach.  It  produces  pain  of  the  most  intense  character, 
which  often  compels  the  strongest  subjects  to  writhe  in 
agony,  and  to  become  bathed  in  a  profuse  perspiration,  irre- 
spective of  the  temperature  of  the  atmosphere.  The  face 
becomes  bloodless,  the  limbs  cold,  the  abdomen  retracted,  and 
the  pulse  small  and  irregular.  The  attacks  are  usually  of 
short  duration,  and  are  most  frequently  terminated  by  eruc- 
tations and  vomiting.  This  disease  is  met  with  in  hysterical 
and  anaemic  subjects,  in  the  course  of  diseases  of  the  uterus 
and  ovaries,  in  spinal  and  cerebral  affections,  and  in  certain 
dyscrasise. 

An  abnormal  condition  of  hunger,  which  is  appeased  by 
small  quantities  of  food,  but  which  returns  at  frequent  inter- 
vals with  an  uncontrollable  desire,  often  interrupting  the 
hours  of  sleep,  is  produced  by  some  disordered  condition 
of  the  vagus,  and  is  called  "houlimia:'  This  affection  is 
met  with  in  hysterical  patients,  after  prolonged  fevers,  in 
severe  forms  of  nervous  debility,  in  syphilis,  insanity,  and 
diabetes. 

By  "polydipsia''  we  mean  an  intolerable  thirst,  depend- 
ent upon  an  hypersesthesia  of  the  nerve  fibers  of  the  mucous 
membrane  of  the  stomach,  pharynx,  and  mouth,  and  prob- 


258  THE  CRANIAL  NEMVES. 

ably  due  to  some  abnormal  state  of  the  pneumogastric  nerve. 
It  is  often  an  associate  symptom  with  boulimia,  and  is  pro- 
duced by  the  same  general  causes. 

The  state  of  '''polyphagia^''  signifies  a  desire  for  excessive 
quantities  of  food.  It  is  supposed  to  exist  when  the  nerve 
fibers  of  the  vagus  distributed  to  the  stomach  are  in  a  state  of, 
anaesthesia,  in  contrast  to  the  condition  producing  the  tw( 
previous  diseases.  It  has  been  found  to  accompany  soften- 
ing of  the  medulla  oblongata,  compression  of  the  roots  of  the 
vagus  by  an  aneurismal  tumor  of  the  vertebral  artery,  atroph; 
of  the  vagi,  neuromata  of  the  vagi,  and  the  morbid  states  oi 
epilepsy,  insanity,  and  hysteria. 

The  nervous  vomiting  which  is  clinically  observed  in  con4 
nection  with  pregnancy,  chlorosis,  hysteria,  digestive  disturb- 
ances, and  gastrodynia,  is  not  to  be  confounded  with  that  of 
local  diseases  of  the  stomach  or  of  the  alimentary  canal,  since 
the  symptom  depends,  purely  and  exclusively,  upon  some  ab- 
normal condition  of  the  nerves,  rather  than  upon  pathological 
changes  in  the  stomach  or  intestine. 

True  paralysis  of  the  gastric  branches  of  the  vagus  must, 
of  necessity,  arrest  the  peristaltic  movement  of  that  organ, 
and  thus  tend  to  favor  the  retention  of  food  within  its  cavity. 
This  may  be  the  explanation  of  the  enormous  enlargement  of 
the  stomach  found  after  chronic  inflammatory  processes  of 
that  organ,  and  also  as  a  sequel  to  cholera,  typhoid  fever, 
and  some  other  blood  poisons.  The  stomach  becomes  en- 
larged in  these  conditions  mainly  by  the  weight  of  the 
retained  food  and  the  pressure  of  the  gases  formed  by  its 
decomposition. 

The  intestinal  and  hepatic  branches  of  the  vagus  are  not 
well  understood  in  their  clinical  phenomena,  but  the  effects 
of  section  of  the  pneumogastric  seem  to  point  to  some  con- 
trolling influence  of  these  fibers  over  the  glycogenic  function 
of  the  liver  and  the  secretion  of  the  intestinal  juices.  The 
effect  of  diseases  of  the  peritonaeum,  or  of  the  abdominal 
viscera,  upon  the  heart  and  respiration,  is  to  be  explained 
either  as  the  direct  result  of  irritation  of  these  fibers,  or  as  a 


THE  SPINAL  ACCESSORY  NERVE.  259 

reflex  act  through  the  sympathetic  nerve  upon  the  cardiac 
and  respiratory  centers,  thus  in  turn  affecting  the  heart  and 
lungs  through  the  vagus. 

THE    SPINAL   ACCESSORY,    OR  ELEVENTH   CRANIAL  NERVE. 

This  nerve  has  a  very  extensive  origin,  since  it  derives  its 
libers  not  only  from  the  medulla  oblongata,  but  also  from  the 
cervical  portion  of  the  spinal  cord.  The  fibers  which  arise 
from  the  medulla  compose  what  is  called  the  "bulbar  por- 
flon,^^m  contrast  to  those  which  arise  from  the  cervical  region 
of  the  spinal  cord,  to  which  the  name  of  ''  spinal  portion^''  is 
sometimes  given.  Such  a  distinction  has  an  importance,  dis- 
tinct from  merely  indicating  the  point  of  origin  of  the  fibers 
composing  the  two  portions  of  the  nerve,  as  the  functions  of 
the  two  are  different. 

If  we  trace  the  filaments  of  origin  of  the  bulbar  portion  of 
the  nerve,  we  can  perceive  that  the  fibers  arise  from  the  lat- 
eral columns  of  the  medulla  oblongata  (its  motor  tract)  and 
escape  from  its  lower  portion,  beneath  the  fibers  of  the  pneu- 
mogastric  nerve.  The  spinal  portion  of  the  nerve  can  be 
traced  between  the  anterior  and  the  posterior  roots  of  the 
first  five  cervical  nerves,  arising  from  between  the  roots  of 
each  nerve  by  a  pair  of  filaments,  with  the  exception  of  the 
last  two,  where  the  filament  going  to  form  the  spinal  accessory 
nerve  is  usually  a  single  one.  These  several  fibers  unite  as 
the  nerve  passes  upward  toward  the  cranium,  thus  causing 
the  spinal  portion  of  the  nerve  to  gradually  increase  in  size. 
In  the  cranium,  the  two  parts  join  to  form  one  nerve,  which 
then  escapes  from  the  jugular  foramen,  in  company  with  the 
pneumogastric  and  glosso-pharyngeal  nerves  and  the  jugular 
V  ein.  The  inferior  meningeal  artery  enters  the  cavity  of  the 
cranium  through  this  foramen,  and  therefore  bears  a  relation 
to  the  nerves  and  vein. 

The  spinal  accessory  nerve  receives  filaments  of  communi- 
cation with  other  nerves,  even  before  it  escapes  from  the 
cavity  of  the  cranium,  since  the  spinal  portion,  on  its  way 


THE  CRANIAL  NERVES. 

upward  to  unite  with  the  bulbar  portion,  is  joined  by  fila- 
ments derived  from  the  two  upper  cervical  nerves  while  in" 
the  spinal  canal. 

After  the  nerve  has  emerged  from  the  jugular  foramen,  it 
gives  off  a  large  branch  to  the  pneumogastric  nerve,  and  occa- 
sionally receives  a  filament  from  the  pneumogastric  in  return ; 


Fig.  94. — Spinal  accessory  nerve.  (Hirschfcld.) 
1,  trunk  of  the  facial  nerve  ;  2,  2,  glosso-pharyngeal  nerve;  3,  3,  pneumogastric;  4,  4,  4, 
trunk  of  the  spinal  accessory ;  5,  sublingual  nerve ;  6,  superior  cervical  ganglion ; 
7,  7,  anastomosis  of  the  first  two  cervical  nerves ;  8,  carotid  branch  of  the  sympa- 
thetic; 9,  10,  11,  12,  13,  branches  of  the  glosso-pharyngeal;  14,  15,  branches  of  the 
facial;  16,  otic  ganglion;  17,  auricular  branch  of  the  pneumogastric;  \9>,  anasto- 
mofdng  branch  from  tJie  spinal  accessory  to  the  pneumogastric  ;  19,  anastomosis  of  the 
first  pair  of  cervical  nerves  with  the  sublingual ;  20,  anastomosis  of  the  spinal  acces- 
sory with  the  second  pair  of  cervical  nerves  ;  21,  pharyngeal  plexus  ;  22,  superior 
laryngeal  nerve ;  23,  external  laryngeal  nerve ;  24,  middle  cervical  ganglion. 

while,  in  its  course  down  the  neck,  it  receives  filaments  of 
communication  from  the  second,  third,  and  fourth  cervical 
nerves,  in  case  these  nerves  do  not  communicate  with  the 
spinal  portion  within  the  spinal  canal. 

After  the  nerve  has  sent  its  upper  filament  to  the  pneumo- 


DISTRIBUTION  OF  SPINAL  ACCESSORY. 


261 


gastric,  at  tlie  Jugular  foramen,  it  may  usually  be  perceived 
to  divide  into  two  branches — an  internal  and  an  external ;  the 
former  of  which  anastomoses  directly  with  the  trunk  of  the 
pneumogastric  nerve,  while  the  latter,  called  the  "muscular 
branch,"  pierces  the  back  part  of  the  upper  third  of  the  sterno- 
mastoid  muscle,  and  terminates  on  the  anterior  surface  of  the 
trapezius.      The  first,    sometimes    called  the    ''anastomotic 


Fig.  95. — Po,sif,i<u   >  n  c' of  the  muscles  of         Fig.  96. — Lateral  view  of  the  muscles  of 
the  larynx.     (Sappey.)  the  larynx.     (Sappcy.) 

Fig.  95. — 1,  posterior  crico-arytenoid  muscle ;  2,  3,  4,  different  fasciculi  of  the  arytenoid 
muscle ;  5,  aryteno-epiglottidean  muscle. 

Fig.  96. — 1,  body  of  the  hyoid  bone;  2,  vertical  section  of  the  thyroid  cartilap^e ;  3,  hori- 
zontal section  of  the  thyroid  cartilage  turned  downward  to  show  the  deep  attach- 
ment of  the  crico-thyroid  muscle  ;  4,  facet  of  articulation  of  the  small  cornu  of  the 
thyroid  cartilage  with  the  cricoid  cartilage;  5,  facet  on  the  cricoid  cartilage;  6, 
superior  attachment  of  the  crico-thyroid  muscle ;  7,  posterior  crico-arytenoid  mus- 
cle; 8,  10,  arytenoid  muscle;  9,  thyro-arytenoid  muscle;  11,  aryteno-epiglottidean 
muscle;  12,  middle  thyro-hyoid  ligament;  13,  lateral  thyro-hyoid  ligament. 

branch,"  is  now  known  to  be  the  nerve  which  supplies  the 
muscles  of  the  larynx^  with  the  exception  of  the  crico-thy- 
roid muscle,'  since  physiological  experiment  confirms  this 
distribution. 

^  The  arytenoid  muscle  of  the  larynx  is  supplied  by  both  the  superior  and  recurrent 
laryngeal  nerves,  the  latter  of  which  carry  most  of  the  spinal  accessory  fibers,  as  is 
shown  in  Fig.  91  of  this  volume.     It  is  also  important  to  remember  that  the  investiga- 
19 


262 


THE  CRANIAL  NERVES. 


\ 


The  second  branch  communicates  with  the  second  and 
third  cervical  nerves,  before  it  pierces  the  sterno-mastoid 
muscle,  and  its  filaments  undoubtedly  furnish  motor  power 
to  that  muscle  and  also  to  the  trapezius.     It  is  proven  by  ex- 


FiG.  97. — A  diagram  of  the  spinal  accessory  nerve. 

I,  the  accessory  portion  oi  the  nerve  arising  from  the  medulla  oblongata;  2,  the  spinal 
portion  of  the  nerve  arising  from  the  spinal  cord  (cervical  region) ;  8,  a  filament 
arising  from  i\\e  first  and  second  cei'vical  nerves  and  joining  the  spinal  portion  of  the 
spinal  accessory  nerve,  before  passing  through  the  foramen  magnum;  4,  the  fora- 
men magnum,  showing  the  spinal  portion  of  the  nerve  entering  the  cranium ;  5,  the 
jugular  foramen,  showing  the  spinal  and  accessory  portions  of  the  nerve  conimuni- 
cating  as  they  pass  through  it ;  6,  the  large  filament  going  to  the  pneumogastric  to 
supply  the  muscles  of  the  larynx,  and  the  S7nall  filament  returning  to  the  trunk  of  the 
spinal  accessory  nerve ;  7,  8,  9,  filaments  of  communication  between  the  spinal 
accessory  nerve  and  the  third,  fourth,  and  fifth  cervical  nerves ;  10,  muscular  branches 
to  the  ste)'no-c!eido-mccstoid  muscle;  11,  muscular  branches  to  the  trapezius  muscle; 
12,  communicating  filaments  from  the  cervical  plexus  of  nciTcs. 

periment,  however,  that  section  of  the  spinal  accessory  nerve 
does  not  produce  total  paralysis  of  these  muscles  ;  and,  from 

tions  of  Bernard  and  Bischoff  have  demonstrated  the  existence  of  other  motor  fibers  to 
the  larynx,  irrespective  of  those  of  the  spinal  accessory,  which  seem  to  control  the  auto- 
matic rcspiratoj'y  movements  of  the  glottis. 


FITSCTIOJ^S  OF  SPINAL  ACCESSORY  NERVE. 


263 


this  fact,  it  is  conclusively  proved  that  some  other  sources  of 
nerve  supply  to  these  muscles  exist,  besides  the  spinal  acces- 
sory filaments. 


A  TABLE   OF  THE   BRANCHES   OF  THE   SPI:N^AL   ACCESSORY   KERVE.* 


Branches  to  tha  pharyngeal  plexus, 
Accessory  or  bulbar   |  Branches  to  the  superior  laryngeal  nerve  (and 
PORTION    (by    means  ^         tlmB  to  i\\Q  depressor  nerve  of  the  heart), 
of  the  sheath  of  the   I   Branches  to  the  recurrent  laryngeal  nerve  (thus 
0.   [  supplying  the  muscles  of  phonation). 

f  Branch  to  the  sfer?io-mas(oid  muscle, 
j  Branch  to  the  trapezius  muscle. 

f  1st  cervical  nevve, 
Communicating  j    2d  cervical  nerve, 
BRANCHES  TO      ]    od  ccrvical  nerve, 
l^  4th  cervical  nerve. 


The  spinal  ac- 
cessory, or 
11th  crani- 
al NERVE. 


pneumogastric  nerve) 


Spinal  portion.  { 


WJh 


fui^ctio:n's  of  the  spin"al  accessory  kerve  akd  the  EFFECTS  or 

SECTION. 

The  experiments  of  Bernard,  to  whose  ingenuity  much  of 
our  present  knowledge  of  the  function  of  the  bulbar  and  spi- 
nal portions  of  this  nerve  is  due,  seem  ^^  ^  ^ 
to  warrant  the  conclusion  that  the  bul- 
bar or  medullary  part  of  the  nerve  pos- 
sesses a  direct  control  upon  the  mus- 
cles of  the  "pharynx  and  larynx^  but 
no  effect  whatever  upon  the  sterno- 
mastoid  and  trapezius  muscles.  Gal- 
vanism of  the  spinal  portion  of  the 
nerve  seems  to  have  a  directly  oppo- 
site effect,  since  the  muscles  of  the 
pharynx  and  larynx  were  unaffected, 
and  the  two  muscles  of  the  neck  to 
which  the  nerve  is  distributed  were 
thrown  into  movement.  It  also  ap- 
pears from  the  results  of  this  great 
experimenter  that  the  nerve  is  essen- 
tially motor  in  its  function  at  its  ori- 
gin from  the  medulla  and  spinal  cord,  but  that  it  gains  sen- 
sory fibers  after  it  leaves  the  cavity  of  the  cranium,  by  means 

'  Modified  from  a  table  in  the  "  Essentials  of  Anatomy"  (Darling  and  Ranney).     Put- 
nam's Sons,  New  York,  1880. 


Fig.  98, — Glottis  seen  ivith  the  la- 
ryngoscope dxiring  the  emis- 
sion of  high-pitched  sounds. 
(Le  Bon.) 

1,  2,  base  of  the  tongue ;  3,  4, 
epiglottis ;  5,  6,  pharynx ;  7, 
arytenoid  cartilages ;  8,  open- 
ing between  the  true  vocal 
cords;  9,  aryteno-epiglotti- 
dean  folds ;  10,  cartilage  of 
Santorini :  11,  cuneiform  car- 
tilage; 12,  superior  vocal 
cords  ;  13,  inferior  vocal 
cords.  ^ 


264  THE  CRANIAL  XERVES. 

of  certain  filaments  of  communication  derived  from  the  cer- 
vical nerves  and  the  pneumogastric.  This  fact  probably  ex- 
plains why  two  points  of  communication  should  exist  be- 
tween the  spinal  accessory  and  the  pneumogastric  nerves  ; 
since,  at  one  point,  the  sensory  filaments  of  the  pneumogas- 
tric were  given  to  the  spinal  accessory,  while,  at  the  other 
point,  the  motor  filaments  of  the  spinal  accessory  were  sent  to 
the  pneumogastric  sheath  for  protection,  until  they  could  be 
distributed  to  the  muscles  of  the  larynx. 

Bernard  and  Bischoff  have  probably  done  more  to  clear  up 
the  disputed  relation  of  the  spinal  accessory  nerve  to  the  mus- 
cles of  the  larynx,  and  thus  to  the  acts  of  phonation  and  res- 
piration,' than  any  of  the  later  investigators  upon  the  physi- 
ology of  the  nervous  system.  When  the  spinal  accessory  nerve 
is  drawn  out  from  the  meduUa  and  spinal  cord  of  an  animal, 
as  can  be  done  with  little  if  any  injury  to  the  nerve,  if  the 
requisite  care  and  skill  be  employed,  the  effect  is  at  once 
manifested  in  the  voice^  which  becomes  hoarse  and  unnatural, 
when  the  nerve  of  one  side  only  is  extracted,  but  entirely 
extinct  when  both  nerves  are  thus  treated.  The  act  of  deglu- 
tition is  also  somewhat  affected,  and  the  trapezius  and  sterno- 
mastoid  muscles  are  paralyzed,  but  only  to  a  partial  extent. 

An  interesting  relation  of  the  spinal  accessory  nerve  to 
the  action  of  the  heart  seems  to  be  well  shown  by  the  experi- 
ments of  Waller,  who  first  called  the  attention  of  the  profes- 
sion to  the  fact  that  extirpation  of  the  roots  of  the  spinal 
accessory  nerve  produced  a  modification  in  the  effects  of  gal- 
vanism of  the  trunk  of  the  pneumogastric  nerve,  provided 
that  sufficient  time  (some  two  weeks)  was  allowed  after  the 
operation  for  the  irritation  so  produced  to  subside.  As  has 
been  mentioned  in  the  previous  lecture  upon  the  pneumogas- 
tric nerve,"  galvanism  of  that  nerve  with  a  powerful  current 
will  arrest  the  action  of  the  heart  in  a  state  of  health,  even  if 

^  The  nerves  concerned  in  the  two  acts  of  phonation  and  respiration  are  not  to  bo 
confounded,  since  it  is  probable  that  the  pneumogastric  nerve  sends  filaments  of  a  motor 
character  to  the  larynx,  which  are  independent  of  the  spinal  accessory  nerve,  and  which 
probably  preside  over  the  respiratory  movements  of  the  glottis,  while  the  spinal  accessory 
nerve  controls  pJionation.  *  See  page  230  of  this  volume. 


fu:n'gtions  of  spinal  accessory  nerve. 


265 


applied  on  one  side  of  the  body.  Now,  Waller  found  that 
after  the  spinal  accessory  nerve  of  one  side  had  been  drawn 
out,  and  the  animal  allowed  to  recover  the  shock  of  the  opera- 
tion, and  to  wait  some  days  for  all  signs  of  irritation  to  sub- 
side, galvanism  of  the  pneumogastric  nerve  of  the  same  side 
no  longer  seemed  to  affect  the  action  of  the  heart.     The  de- 


FiG.  99. —  The  spinal  accessory  nerve.      (Sappey.) 

1,  large  root  of  the  fifth  nerve ;  2,  ganglion  of  Gasser  ;  3,  ophthalmic  division  of  the  fifth  ; 
4,  superior  maxillary  division ;  5,  inferior  maxillary  division ;  6,  10,  lingual  branch 
of  the  fifths  containing  the  filaments  of  the  chorda  tympani ;  Y,  branch  from  the  sub- 
lingual to  the  lingual  branch  of  the  fifth ;  8,  chorda  tympani ;  9,  inferior  dental 
nerve ;  10,  terminal  branches  of  the  gustatory  nerve ;  11,  submaxillary  ganglion  ;  12, 
mylo-hyoid  branch  of  the  inferior  dental  nerve;  13,  anterior  belly  of  the  digastric 
muscle;  14,  section  of  the  mylo-hyoid  muscle;  15,  18,  glosso-pharyngeal  nerve;  16, 
ganglion  of  Andersch  ;  17,  branches  from  the  glosso-pharyngeal  to  the  stylo-glossus 
and  the  stylo-pharyngev^  muscles;  19,  19,  pneumogastric;  20,  21,  ganglia  of  the 
pneumogastric ;  22,  22,  superior  laryngeal  nerve ;  23,  spinal  accessory  ;  24,  25,  26, 
27,  28,  sublingual  nerve  and  branches. 

pressor  nerve  of  the  lieart,  which  arises  from  both  the  supe- 
rior laryngeal  and  pneumogastric  nerves,  since  it  has  two 
heads,  must,  therefore,  be  in  some  way  connected  with  the 


266  THE  CRANIAL  NERVES. 

spinal  accessory  nerve.  It  may,  therefore,  be  stated  mth  as 
muclx  positiveness  as  any  physiological  point  can  be  laid 
down,  that  the  communicating  filament  given  off  by  the  spi- 
nal accessory  nerve  to  the  pneumogastric  controls  the  heart 
fibers  as  well  as  the  muscles  of  phonation. 

The  distribution  of  the  spinal  accessory  nerve  to  only  two 
of  the  muscles  of  the  neck — the  sterno-mastoid  and  the  tra- 
pezius— would  naturally  suggest,  to  the  inquiring  mind,  why 
these  muscles  should  have  been  singled  out  as  particularly 
associated  with  this  nerve.  Throughout  this  entire  course  of 
lectures  I  have  frequently  called  your  attention  to  the  fact, 
which  can  not  be  too  often  repeated,  that  the  distribution  of 
nerves  to  muscles  always  denotes  a  purpose  on  the  part  of 
Nature,  and  a  similarity  of  function  in  the  muscles  supplied 
by  the  same  nerve,  if  we  will  but  search  for  it.  Now,  we 
have  already  seen  that  the  spinal  accessory  nerve  is  chiefly 
destined  to  control  the  muscles  of  phonation^  since  other 
nerve  fibers  go  to  the  larynx,  which  assist  in  moving  the  vocal 
cords  during  the  opening  of  the  glottis,  previous  to  each  in- 
spiratory act ;  therefore,  the  spinal  accessory  nerve  can  not 
be  said  to  be  directly  concerned  with  the  respiratory  func- 
tion. If  we  will  study  the  attitude  assumed  by  a  vocalist  in 
the  act  of  singing  (and  it  is  in  the  singing  act,  rather  than 
that  of  talking,  that  we  see  the  mechanism  of  jDhonation  best 
displayed,  since  it  requires  more  of  a  muscular  effort  than 
the  simple  articulation  of  words),  we  shall  perceive  that  the 
sterno-mastoid  and  the  trapezius  muscles  are  important  fac- 
tors in  the  production  of  voice^  as  they  tend  to  fix  the  shoul- 
ders (that  is,  the  scapulae  and  the  clavicles)  and  also  the 
upper  part  of  the  sternum.  In  all  vocal  efforts,  the  first  act 
necessary  to  its  performance  is  a  full  inspiratory  effort,  which 
can  only  be  performed  by  first  calling  into  play  those  muscles 
which  render  the  upper  portion  of  the  chest  and  the  bones  of 
the  shoulder  immovable,  so  as  to  have  a  fixed  point  from 
which  the  true  inspiratory  muscles  can  act  upon  the  ribs  and 
their  cartilages ;  and  it  can,  therefore,  be  understood  why 
these  muscles  should  properly  be  placed  under  the  control  of 


RELATION'S  OF  SPmAL  ACCESSORY  NERVE  TO  VOICE.    267 

that  nerve  which  also  controls  the  muscles  which  regulate 
the  position  and  tension  of  the  vocal  cords  during  the  expira- 
tory effort,  and  thus  causes  the  proper  vibrations  of  these 
cords,  and  regulates  the  note  which  follows. 

In  animals,  where  the  muscular  branch  of  the  spinal  acces- 
sory nerve  has  been  severed,  a  difficulty  in  progression  has 
been  observed  by  Bernard,  and  a  peculiar  shortness  of  breath 
after  violent  exercise.  The  difficulty  in  locomotion  is  not 
present  in  man,  on  account  of  certain  anatomical  peculiarities 
which  render  the  arm  unnecessary  for  progressive  motion, 
which  is  not  the  case  with  quadrupeds  ;  but  the  shortness  of 
breath  which  has  been  observed  would  probably  exist  in  a 
man  after  violent  exercise,  or  when  any  demand  for  an  exces- 
sively full  inspiratory  effort  occurred,  if  the  trapezius  or  the 
sterno-mastoid  muscles  were  paralyzed. 

A  theory  advanced  by  Hilton,'  as  explanatory  of  the  pe- 
culiarity of  the  course  of  the  spinal  accessory  nerve,  deserves 
mention,  since  it  tends  possibly  to  explain  not  only  the  irreg- 
rJar  course  of  the  nerve,  but  also  the  object  of  the  communi- 
cation of  the  sub-occipital  with  the  spinal  accessory  nerves 
within  the  spinal  canal.  According  to  this  author,  the  spi- 
nal portion  of  this  nerve  becomes  joined  to  the  sub-occipi- 
tal before  it  enters  the  cranium,  and,  since  that  nerve  is 
almost  exclusively  a  motor  nerve,  what  object  could  the 
spinal  accessory,  which  is  itself  a  motor  nerve,  have  in  send- 
ing additional  filaments  to  the  sub-occipital,  unless  it  was  for 
the  purpose  of  sending  fibers  to  the  inferior  oblique,  the  two 
posterior  recti,  and  the  complexus  muscles  of  the  neck? 
N^ow,  when  a  motor  impulse  is  sent  out  by  means  of  the 
spinal  accessory  nerve,  the  effects  reach  those  muscles  first 
Avhich  are  nearest  to  its  place  of  origin ;  hence,  the  muscles 
of  the  sub-occipital  region  are  caused  to  contract  before  the 
trapezius  or  the  sterno-mastoid  muscles,  and,  by  so  doing,  the 
head  is  drawn  backward  before  the  latter  muscles  act,  thus 
greatly  assisting  them  to  raise  the  thorax,  as  well  as  in  ren- 
dering the  head  a  fixed  point  during  the  inspiratory  act. 

1  "Rest  and  Pain,"  London,  1S72. 


268  THE  CRANIAL  NERVES. 

CLINICAL   POINTS   PERTAINING  TO   THE   SPINAL  ACCESSORY  NERYE. 

Like  all  motor  nerves,  the  spinal  accessory  may  exhibit 
the  condition  of  spasm  or  paralysis  in  the  parts  supplied  by 
it ;  if  subjected  to  some  source  of  irritation,  as  in  the  tirst  in- 
stance, or  to  some  lesion  which  destroys  its  power  of  con- 
duction, as  in  the  latter.  The  spasm  dependent  upon  irrita- 
tion of  this  special  nerve  seems  to  be  confined  exclusively  to 
the  sterno-mastoid  and  trapezius  muscles.  They  may  be  uni- 
lateral or  bilateral,  and  the  muscular  contractions  may  be 
either  of  the  tonic  or  clonic  variety. 

Both  of  these  types  of  spasm  are  met  with  in  connection 
with  reflex  irritation  originating  in  some  of  the  remote  vis- 
cera ;  hence  they  are  not  infrequent  in  severe  types  of  hysteri- 
cal affections.  They  may  also  be  produced  by  diseases  affect- 
ing the  upper  cervical  vertebrae,  by  certain  forced  movements 
of  the  head,  by  exposure  to  cold  and  wet,  and  by  local  dis- 
eases of  the  brain  and  spinal  cord.  When  we  consider  the 
intimate  connection  which  this  nerve  has  with  the  spinal  cord, 
as  well  as  the  medulla  oblongata  and  brain,  we  can  better 
appreciate  the  difficulty  which  often  arises  in  locating  the 
exact  seat  of  the  irritation  which  is  producing  these  spasmodic 
movements.  There  are  reported  cases  to  prove  that  tumors 
of  the  brain  or  spinal  cord,  softening  of  either  of  these  re- 
gions, meningeal  inflammation  of  the  brain  or  cord,  injuries 
to  the  skuU  or  upper  cervical  vertebrae,  and  caries,  periostitis, 
and  tumors  of  the  upper  cervical  vertebrae,  may  all  be  excit- 
ing causes  of  this  spasmodic  action. 

Tonic  Spasm  of  the  Sterno-mastoid  and  Trapezius  Mus- 
cles.— When  the  sterno-mastoid  muscle  is  the  seat  of  tonic 
spasm,  the  head  is  so  drawn  that  the  ear  approaches  the 
clavicle,  the  occiput  the  tip  of  the  shoulder,  and  the  chin  isj 
so  rotated  that  it  points  toward  the  opposite  side.  This  con- 
dition is  of  longer  or  shorter  duration,  and  often  shows  a 
marked  tendency  to  become  a  permanent  contracture.  Dur- 
ing the  early  paroxysms,  the  patient  can  not  rectify  the  dis- 
placement of  the  head  by  his  own  voluntary  efforts,  and  pas- 


CLINICAL  RELATIONS  OF  SPINAL  ACCESSORY  NERVE.    269 

sive  motion  is  strongly  resisted.  The  early  periods  of  the 
paroxysm  are  often  accompanied  by  sharp  pains.  When  the 
disease  has  become  chronic,  the  deformity  of  the  neck  is  as- 
sociated with  n^  permanent  curvature  of  the  cermcal  mrtel)rce 
and  a  corresponding  curve  of  a  compensatory  character  in  the 
dorsal  and  lumbar  regions.  A  rare  case  of  bilateral  tonic 
spasm  of  the  stemo-mastoid  muscles  is  reported  by  Duchenne, 
in  which  the  chin  was  approximated  to  the  breast. 

The  trapezius  muscle  may  also  be  the  seat  of  tonic  spasm. 
In  this  case,  the  head  is  inclined  toward  the  affected  side, 
the  occiput  is  drawn  toward  the  shoulder,  the  shoulder  itself 
is  raised,  and  the  scapula  is  drawn  inward.  The  chin  is  not 
rotated  toward  the  unaffected  side,  as  in  the  case  of  the 
sterno-mastoid  muscle.  All  attempts  to  bring  the  head  into 
its  proper  relation  to  the  trunk  create  a  rigidity  and  sensi- 
tiveness over  the  region  of  the  trapezius. 

Clonic  Spasm  of  the  Sterno-mastoid  and  Trapezius  Mus- 
cles.— This  variety  of  spasm,  which  is  dependent  upon  the 
same  general  list  of  causes  as  the  tonic  form,  may  be  uni- 
lateral or  bilateral.  Either  of  the  muscles  supplied  by  the 
spinal  accessory  may  be  affected  alone,  or  the  sterno-mastoid 
and  trapezius  may  contract  alternately.  If  the  spasm  be  con- 
fined to  one  muscle  and  of  the  unilateral  type,  the  deflection 
of  the  head  will  be  the  same  as  in  the  tonic  spasm,  except 
that  the  duration  of  the  contraction  will  be  for  a  shorter 
period,  and  of  a  convulsive  variety  ;  while,  if  the  two  muscles 
of  one  side  contract  alternately,  the  attitude  of  the  head  will 
be  constantly  changing  from  the  condition  due  to  contraction 
of  the  one  to  that  produced  by  the  other.  When  the  sterno- 
mastoid  muscles  of  both  sides  act  simultaneously  in  a  spas- 
modic contraction,  a  peculiar  '' nodding  movement"  is  per- 
ceived. You  can  understand  how  all  forms  of  combina- 
tions can  be  made  between  the  two  muscles  of  either  side, 
and  a  proportionate  variety  of  spasmodic  attitudes  will  be 
the  result.  All  of  these  contractions  occur,  for  the  most 
part,  in  paroxysms^  often  lasting  for  a  day,  and  not  infre- 
quently coming  on  with  such  violence  and  frightful  vehe- 


270  THE  CRANIAL  NERVES. 

mence  that  the  head  is  tossed  to  and  fro  with  great  force, 
making  the  life  of  the  patient  miserable.  In  some  instances, 
the  spasm  is  almost  continuous.  Sleep,  however,  usually 
brings  rest,  though  this  is  often  prevented  or  delayed. 

In  unilateral  clonic  spasm  of  the  sterno-mastoid  muscle, 
the  adjacent  muscles  of  the  face,  jaw,  and  arm  are  occasional- 
ly thrown  into  simultaneous  action.  The  scaleni  muscles  are 
also  sometimes  brought  into  active  play,  and  their  forcible 
compression  of  the  brachial  plexus  of  nerve  and  the  veins 
of  the  neck  has  been  known  to  result  in  stiffness,  anaes- 
thesia, and  oedema  of  the  arm,  after  such  an  attack  had  sub- 
sided. 

The  nodding  movement  produced  by  the  bilateral  clonic 
spasm  of  the  sterno-mastoid  muscles  is  sometimes  called  the 
*' salaam  convulsion  of  Newnham."  It  is  rarely  seen  in 
adults,  but  in  children  it  is  not  infrequent.  Should  it  occur 
during  dentition,  the  spasm  may  be  associated  with  convulsive 
movements  of  the  facial  muscles,  with  strabismus,  and  even 
with  general  convulsions  and  a  loss  of  consciousness.  Bi- 
lateral spasm  of  the  muscles  supplied  by  the  spinal  accessory 
nerve  has  been  known  to  terminate  in  epilepsy,  insanity,  and 
paralysis ;  and,  when  the  various  causes  of  the  condition  are 
reviewed,  this  will  appear  but  the  natural  sequence  of  the 
further  progress  of  some  of  the  diseases  mentioned.  Should 
reflex  irritation,  as  in  dentition,  worms,  hysteria,  etc.,  exist, 
or  the  spasm  be  dependent  upon  rheumatic  origin,  exposure 
to  cold  or  dampness,  traumatism,  caries,  and  other  curable 
conditions,  the  results  will  be  arrested  when  the  exciting- 
cause  has  been  removed. 

Paralysis  of  the  Sterno-mastoid  and  Trapezius  Mus- 
cles.— These  muscles  may  be  affected  with  a  total  arrest 
of  their  nerve  power  by  lesions  of  the  motor  columns  of  the 
spinal  cord,  resulting  in  progressive  muscular  atrophy ;  by 
fracture  of  the  cervical  vertebrae ;  diseases  of  the  vertebrae 
near  the  skull  and  also  of  the  cranial  bones  ;  injuries  to  the 
nerve,  such  as  cuts,  stabs,  gunshot  wounds  of  the  neck ;  and 
compression  of  the  nerve  from  peripheral  causes,  as  in  the 


CLINICAL   RELATIONS  OF  SPINAL  ACCESSORY  NERVE.    271 

case  of  tumors  of  the  neck,  swelling  of  the  lymphatic  glands 
of  the  neck,  abscesses,  neuromata,  etc. 

The  sterno-mastoid  or  the  trapezius  may  be  paralyzed  in- 
dependently of  the  other,  or  they  may  both  be  affected  si- 
multaneously, according  as  the  cause  affects  the  entire  nerve  or 
only  some  individual  branch.  The  paralysis  may,  in  some 
instances,  be  bilateral,  provided  the  exciting  cause  be  central 
and  involve  the  parts  in  the  median  line,  or  so  extensive  as  to 
press  upon  the  trunks  of  both  spinal  accessory  nerves.  A 
case  of  bilateral  paralysis  following  progressive  muscular 
atrophy  of  the  muscles  of  the  neck  is  reported  by  Rosenthal, 
where  the  patient  was  obliged  to  support  the  head  by  a  collar 
made  of  pasteboard  ;  but  this  was  rather  the  consequence  of 
the  general  atrojDhy  of  the  muscles  than  the  effect  of  the  pa- 
ralysis of  the  two  muscles  supplied  by  the  spinal  accessory. 

In  unilateral  'paralysis  of  the  sterno-mastoid  muscle^  the 
voluntary  rotation  of  the  head  toward  the  unaffected  side  is 
performed  with  difficulty  ;  the  chin  is  turned  toward  the  af- 
fected side,  on  account  of  the  unopposed  action  of  the  healthy 
muscle  ;  the  chin  is  also  slightly  elevated,  and  the  paralyzed 
muscle  does  not  stand  out  vdth  equal  prominence  with  its 
fellow,  when  the  chin  is  supported  by  the  hand  of  the  physi- 
cian, and  direction  is  given  to  the  patient  to  try  and  depress 
the  chin  toward  the  chest.  If  this  unilateral  paralysis  be 
long  continued,  the  contracture  of  the  healthy  muscles  pro- 
duces the  condition  of  ''  torticollis." 

When  a  bilateral  paralysis  of  the  sterno-mastoid  muscles 
is  developed,  the  head  is  held  straight,  and  its  rotation,  es- 
pecially with  the  chin  elevated,  is  performed  with  extreme 
difficulty.  The  neck  appears  thin,  and  the  lateral  aspect  of 
that  region  is  markedly  flattened,  since  the  normal  prominence 
of  the  sterno-mastoid  muscle  is  wanting.  The  same  test,  as 
mentioned  above,  when  the  chin  is  supported  by  the  hand  of 
the  physician,  shows  a  great  loss  of  power  in  attempting  to 
flex  the  head  upon  the  chest. 

The  effects  of  unilateral  paralysis  of  the  trapezius  mus- 
cle are  most  marked  in  the  region  of  the  scapula.     This  bone 


272  THE  CRANIAL  NERVES. 

appears  to  be  drawn  downward  and  forward  ;  its  inferior  angle 
lies  closer  to  the  vertebral  column  than  that  of  its  fellow,  and 
its  upper  part  is  more  widely  separated  from  the  vertebrae. 
The  clavicle  is  caused  to  stand  off  from  the  chest,  on  account 
of  the  acromion  being  drawn  downward  and  forward  by  the 
weight  of  the  upper  extremity  and  the  pectoral  and  the  leva- 
tor anguli  scapulae  muscles ;  hence,  the  supra- clavicular  fossa 
is  apparently  enlarged,  in  comparison  with  the  healthy  side. 
It  is  to  be  remembered,  however,  by  you  that  the  trapezius, 
unlike  many  others  in  the  body,  often  manifests  paralysis  in 
portions  of  the  muscle  ;  so  that  the  symptoms  of  this  type  of 
unilateral  paralysis  admit  of  many  modifications,  in  accord- 
ance with  the  extent  and  limits  of  the  disease.  Thus,  the 
position  of  the  scapula  will  vary  with  the  paralysis  of  the 
upper,  middle,  or  lower  fibers  of  the  muscle ;  the  power  of 
elevation  of  the  arm  will  be  greatly  impaked  if  the  upper 
fibers  are  paralyzed  ;  while  the  approximation  of  the  scapula 
to  the  vertebral  column  is  very  much  impaired  when  the 
middle  fibers  are  alone  involved. 

When  the  trapezei  muscles  are  affected  with  bilateral 
paralysis^  in  addition  to  the  symptoms  described,  which  wall 
now  be  perceived  upon  both  sides,  the  hacJc  will  appear 
broader  and  more  arched^  since  the  scapulae  are  lowered  and 
drawn  outward,  while  they  are  also  more  prominent.  Some 
difficulty  may  also  be  experienced  in  maintaining  the  head  in 
an  upright  position,  since  it  naturally  tends  to  sink  toward 
the  chest. 


THE   HYPO-GLOSSAL,   OR  TWELFTH  CRANIAL  NERVE. 

This  nerve  is  sometimes  called  the  sublingual  nerve^  thus 
using  a  Latin  rather  than  Greek  term  to  express  the  same 
idea,  viz.,  that  the  nerve  passes  underneath  the  tongue.  It  is 
the  last  of  the  cranial  nerves,  and  is  intimately  associated  with 
all  those  movements  in  which  the  tongue  takes  an  important 
part,  such  as  the  acts  of  talking,  singing,  mastication,  and 
deglutition.     The  point  of  external  origin  of  this  nerve  is  a 


THE  HYPO-GLOSSAL,   OR   TWELFTH  NERVE. 


273 


groove  between  the  olivary  body  of  the  medulla  oblongata 
and  the  anterior  pyramid^  below  the  point  of  escape  of  the 
ninth,  tenth,  and  eleventh  nerves.  Its  deep  fibers  can  be 
traced  to  a  nucleus  in  the  floor  of  the  fourth  ventricle,  and 
it  is  probable  that  some  of  them  decussate  in  the  median  line 
of  the  floor  of  that  cavity,  thus  passing  to  the  opposite  side 
of  the  medulla.  The  nerve  escapes  from  the  cavity  of  the 
cranium  by  the  anterior  condyloid  foramen. 


Fig.  100. — Distribution  of  the  hypo-glossal  nerve.     (Sappey.) 

1,  root  of  the  fifth  nerve;  2,  ganglion  of  Gasser ;  3,  4,  5,  6,  7,  9,  10,  12,  branches  and 
anastomoses  of  the  fifth  nerve  ;  11,  submaxillary  ganglion;  13,  anterior  belly  of  the 
digastric  muscle  ;  14,  section  of  the  mylo-hyoid  muscle  ;  15,  glosso-pharyngeal  nerve ; 
16,  ganglion  of  Andersch  ;  17,  18,  branches  of  the  glosso-pharyngeal  nerve;  19,  19, 
pneumogastric ;  20,21,  ganglia  of  the  pneumogastrie ;  22,  22,  superior  laryngeal 
branch  of  the  pneumogastric  ;  23,  spinal  accessory  nerve ;  24,  hypo-glossal  nerve  ;  25, 
dcsccndens  noni ;  26,  ihyro-hyoid  branch  ;  27,  terminal  branches ;  28,  two  branches^ 
one  to  iJie  gcnio-hyo-glossus  and  the  other  to  the  genio-hyoid  miAscle. 

After  the  nerve  escapes  from  the  cranium,  it  gives  a  fila- 
ment of  communication  to  the  sympathetic  nerve,  which  joins 


274: 


THE  CRANIAL  NERVES. 


the  superior  cervical  ganglion  ;  another  to  the  jpneumo gastric 
nerve;  two  or  three  branches  to  the  upper  cervical  nerves; 


Fig.  101. — Anastomotic  loop  formed  by  the  descending  branch  of  the  hypo-gloi^sal  and  the 
internal  descending  branch  of  the  cervical  plexus.     (After  Hirschfeld.) 

1,  lingual  nerve  passing  transversely  upon  the  hyo-glossus  muscle ;  2,  2,  trunk  of  the 
pneumogastric ;  3,  superior  laryngeal  nerve ;  4,  external  laryngeal  nerve ;  5,  external 
branch  of  the  spinal  accessory  supplying  the  stcrno-mastoid  and  trapezius ;  6,  ante- 
rior branch  of  the  second  pair  of  cervical  nerves ;  7,  anterior  branch  of  the  third 
pair;  8,  anterior  branch  of  the  fourth  pair;  9,  origin  of  the  phrenic;  10,  origin  of 
the  subclavian  nerve;  11,  origin  of  the  anterior  thoracic  nerves  of  the  brachial 
plexus;  12,  middle  portion  of  the  trunk  of  the  hypo-glossal;  13,  desccndens  noni ; 
14,  internal  descending  branch  of  the  cervical  plexus,  forming,  with  the  preceding,  a 
loop  with  its  convexity  directed  downward  ;  15,  inferior  branch  from  this  loop,  sup- 
plying the  sterno-thyroid  muscle ;  1 6,  superior  branch  distributed  to  the  sterno-hyoid 
muscle;  17,  another  branch  still  higher  up,  and  distributed  to  the  same  muscle; 
18,  middle  branches  from  the  loop;  19,  filament  extending  as  far  as  the  lower  ex- 
tremity of  the  sterno-thyroid  ;  20,  branch  given  off  by  the  hypo-glossal  to  the  thyro- 
hyoid;  21,  branches  of  anastomosis  between  the  hypo  glossal  and  lingual;  22,  ter- 
minal portion  of  the  trunk  of  the  hypo-glossal. 

and,  finally,  a  communicating  branch  to  the  gustatory  'branch 
of  t\ie  fifth  nerve. 


DISTRIBUTION^  OF  HYPO-GLOSSAL  NERVE.  275 


Fig,  102. — A  diagram  of  the  hypo-glossal  and  its  branches. 

1,  trunk  of  hypo-glossal  werw, escaping  from  the  medulla  oblongata;  2,  anterior  condyloid 
foramen ;  3,  filaments  of  communication  to  i\\Q  pneumogastric  nerve  ;  4,  filaments  of 
communication  to  the  superior  cervical  ganglion  of  the  sympathetic  system  ;  5,  fila- 
ments of  communication  to  the  first  and  second  spinal  nerves  of  the  cervical  region ; 
6,  the  dcscendens  noni  nerve,  forming  a  loop  with  the  comm.unicans  noni  nerve  (19) 
and  giving  off  muscular  branches  from  the  loop  ;  V,  muscular  filaments  to  the  thyro- 
hyoid muscle  ;  8,  muscular  filament  to  the  geniohyoid  muscle  ;  9,  muscular  fila- 
ment to  the  genio-hyo-glossus  muscle  ;  10,  muscular  filament  to  the  hyo-glossus  muscle  ; 
11,  muscular  filament  to  the  stylo-glossus  muscle;  12,  the  occipital  artery,  around 
which  the  hypo-glossal  nerve  winds,  before  reaching  the  tongue  ;  13,  a  branch  of  the 
communicans  noni  nerve,  derived  from  the  second  cervical  nerve ;  14,  a  branch  of 
the  communicans  wowi  nerve,  derived  from  the  third  cervical  nerve  ;  15,  a  muscular 
branch  to  the  omo-hyoid  muscle  (anterior  belly);  16,  a  muscular  branch  to  the  sterno- 
hyoid muscle;  IV,  a  muscular  branch  to  the  sterna-thyroid  va\xsc\Q  \  18,  a  muscular 
branch  to  the  omo-hyoid  (posterior  belly) ;  19,  the  commtmicans  noni  nerve,  joining 
the  descendetis  noni  nerve  to  form  a  loop. 


276  THE  CRANIAL  NERVES. 

Its  first  branch  of  distribution  is  named  the  descendens 
noni  (the  descending  of  the  ninth  nerve),  so  called  since  this 
nerve  was  classed  by  Willis  as  the  ninth.  This  branch 
passes  down  the  neck  to  supply  the  stemo-hyoid,  sterno- 
thyroid, and  omo-hyoid  muscles,  and  then  joins  the  com- 
municans  noni  nerve  (a  branch  of  the  cervical  plexus),  to 
form  a  loop,  from  which  terminal  filaments  are  given  off. 
The  other  branches  of  the  nerve  are  distributed  to  the  thyro- 
hyoid muscle  (which  usually  has  a  separate  filament  of  its 
own),  the  stylo-glossus,  the  hyo-glossus,  genio-hyoid,  genio- 
hyo-glossus,  and  the  intrinsic  muscles  of  the  tongue.  It  will 
thus  be  seen  that  the  hypo-glossal  nerve  is  the  motor  nerve  of 
all  the  muscles  which  tend  to  depress  the  larynx  and  the 
hyoid  hone^  after  they  have  been  raised  during  the  second 
stage  of  the  act  of  deglutition  (the  muscles  of  the  infra-hyoid 
region),  also  to  one  of  the  supra-hyoid  region,  the  genio-hy- 
oid, and  to  most  of  the  muscles  which  act  upon  the  tongue. 

In  the  preceding  diagrammatic  figur^,  the  branches  of  the 
hypo-glossal  nerve  are  shown,  and  the  general  course  of  the 
nerve  is  made  more  clear  than  can  be  done  by  a  verbal  de- 
scription. 

TABLE   OF  THE   BRANCHES   OF  THE   HYPO-GLOSSAL   NERVE.* 

f  To  the  ganglion  of  the  trunk  of  the  pncu- 
mogastric  nerve, 
Branc\es  of      '   '^^  *^^  superior  cervical  ganglion  of  the 
mmunLatdn    ^   ^      Sympathetic, 

To  the  loop  between  the  first  and  second 
cervical  nervj s, 
,  To  the  gustatory  nei've. 
""  Descendens  noni  nerve, 
To  thyro-hyoid  nerve, 
To  genio-hyoid  muscle, 
distHb^Z      <  To  stylo-glossus  muscle, 
To  hyo-glossus  muscle, 
To  genio-hyo-glossu8  muscle. 
To  the  intrinsic  muscles  of  the  tongue. 


THE  HYPO-GLOSSAL, 
ORTWELFTHCRA-  -{ 
NIAL  NERVE. 


communication. 


Branches  of 


FUNCTIONS  OF  THE  HYPO-GLOSSAL  NERVE. 

The  fact  that  the  hypo-glossal  nerve  arises  from  the  motor 
portion  of  the  spinal  cord  (when  taken  in  connection  with  the 

1  Copied  from  the  "  Essentials  of  Anatomy  "  (Darling  and  Ranney).      Putnam's  Sons, 
New  York,  1880. 


FUNCTIONS   OF  THE  HYPO-GLOSSAL  NERVE.  277 

absence  of  any  ganglionic  enlargement  upon  the  trunk  of  tlie 
nerve)  would  seem  to  indicate  that  the  function  of  the  hypo- 
glossal is  essentially  motor ;  and  such  a  conclusion  is  sus- 
tained by  the  experiments  of  Longet,  who  found  the  nerve 
incapable  of  transmitting  any  sensory  impressions  when  the 
roots  were  subjected  to  irritation. 

Mayo  and  Magendie,  however,  first  proved  that  the  nerve 
possessed  sensory  filaments,  after  it  had  escaped  from  the 
cavity  of  the  cranium,  which  results  have  since  been  confirmed 
by  most  of  the  later  physiologists.  We  can  easily  explain 
this  acquired  power  of  sensibility  which  the  nerve  exhibits, 
by  the  branches  of  communication  which  it  receives  from  the 
pneumogastric,  the  cervical  nerves,  and  the  gustatory  branch 
of  the  fifth  nerve ;  so  that  there  is  little,  if  any,  reason  to 
doubt  that  the  original  fibers  of  the  nerve  itself  are  purely 
motor  in  function. 

In  connection  with  the  glosso-pharyngeal  nerve,  I  entered 
into  a  somewhat  extended  discussion  of  the  mechanism  of  the 
act  of  deglutition  ; '  and  the  same  subject  might,  with  equal 
propriety,  be  again  repeated  in  connection  with  the  hypoglos- 
sal nerve,  since  both  are  intimately  associated  with  those 
complex  movements.  It  will  suffice,  however,  to  again  call 
attention  to  the  fact,  that  movements  of  the  tongue  were  of 
the  greatest  importance  in  swallowing,  since  that  organ  not 
only  conveyed  the  bolus  to  the  back  portion  of  the  mouth, 
and,  when  liquids  were  to  be  swallowed,  helped  to  form  a 
tube  through  which  a  suction  force  could  be  exerted,  but  also 
assisted  in  the  prevention  of  food  from  entering  the  cavity  of 
the  larynx. 

CLINICAL   POINTS   PERTAINING  TO  THE   HYPO-GLOSSAL  NERVE. 

When  this  nerve  is  divided  in  animals,  the  sense  of  taste 
remains  and  the  tongue  retains  its  normal  sensitiveness ;  but 
the  power  of  movement  is  utterly  destroyed  if  the  nerves  of 
both  sides  are  simultaneously  cut.  As  a  natural  consequence, 
the  first  stage  of  the  act  of  deglutition  is  materially  embar- 
go ^  See  page  226  of  this  volume. 


278 


THE  CRANIAL  NERVES. 


rassed,  and  the  second  stage  is  liable  to  be  associated  with  the 
entrance  of  fluid,  if  swallowed,  into  the  cavity  of  the  larynx. 
When,  in  the  human  subject,  this  nerve  is  impaired,  either 
as  a  special  type  of  paralysis  or  during  an  attack  of  hemi- 
plegia, the  power  of  protrusion  of  the  tongue  from  the  mouth 
in  a  straight  line  is  lost,  and  that  member  becomes  de- 
flected toward  the  side  which  is  paralyzed,  since  the  genio- 
hyo-glossus  muscle  is  unopposed.  A  disease  of  rather  rare 
occurrence,  in  which  the  hypo-glossal  nerves  of  both  sides  are 
paralyzed,  and,  in  addition,  the  orbicular  muscle  of  the  mouth, 
and,  not  infrequently,  the  intrinsic  muscles  of  the  larynx,  is 
described  by  Duchenne  ; '  and,  since  his  article,  it  has  been 


Fig.  103. — Glosao-lahio-laryngeal  paralysis.     (After  Hammond.) 


written  upon  by  most  of  the  later  authors  under  the  names 
of  glosso-labio-laryngeal  paralysis,  glossoplegia,  etc.  In  this 
type  of  disease  the  tongue  lies  motionless  and  trembling  in  the 


De  I'electrisation  localia^e,"  Paris,  1861. 


BUCHENN-E'S  DISEASE.  279 

floor  of  the  mouth,  if  all  power  of  motion  be  paralyzed  ;  but, 
if  paresis  only  exist,  it  can  be  imperfectly  protruded  with 
difiiculty,  and  is  tremblingly  and  slowly  retracted.  If  one 
side  be  affected,  the  sound  side  becomes  full  and  promi- 
nent, in  comparison  with  the  affected  side,  when  called  into 
action.  The  peculiar  trembling  character  of  the  move- 
ment of  the  tongue  in  bilateral  paresis  is  observed  in  every 
motion  which  the  patient  attempts  to  perform  with  that  or- 
gan, and  all  the  motions  are  slowly  and  imperfectly  accom- 
plished. 

The  most  important  effects  of  the  paralytic  state  of  the 
muscles  are  shown  in  attempts  at  mastication  and  speech. 
The  food  is  no  longer  properly  placed  between  the  teeth ;  is 
with  great  difiiculty  carried  to  the  back  part  of  the  mouth ; 
and  frequently  regurgitates  into  the  mouth,  when  attempts 
are  made  to  swallow.  The  saliva  is  secreted  in  large  quanti- 
ties, and  is  swallowed  with  extreme  difiiculty,  so  that  the 
patient  is  constantly  obliged  to  expectorate. 


Fig.  104. —  Glosso-labio-laryngeal  paralysis.     (After  Hammond.) 


The  disturbances  of  speech  may  present  themselves  with 
varying  degrees  of  intensity.  In  those  cases  where  the  tongue 
is  affected  upon  one  side  only  (and  a  state  of  paresis  exists, 
rather  than  that  of  complete  paralysis  of  motion),  only  those 
sounds  which  require  the  aid  of  the  tongue  to  be  pronounced 


280  THE  CRANIAL  NERVES. 

are  indistinctly  and  incompletely  articulated.  These  letters 
are  5,  sch^  Z,  e^  ^,  and,  at  a  later  period,  ^,  ^,  r,  etc. 

When  the  paralysis  is  bilateral,  and  the  tongue  has  under- 
gone atrophy,  the  speech  becomes  exceedingly  indistinct, 
muttering  and  inarticulate,  so  that  the  patient  can  hardly 
express  himself  in  sounds  that  can  be  understood  by  those  in 
constant  communication  with  him.  The  act  of  singing  is 
always  affected  in  even  the  mild  forms  of  lingual  paralysis  ; 
and  the  falsetto  notes  are  particularly  affected,  since  the 
tongue  plays  an  important  part  in  so  directing  the  sound  as 
to  give  it  its  proper  timbre. 

The  effects  of  lingual  paralysis  must  not  be  confounded 
with  spasm  of  the  lingual  muscles  (the  act  of  stuttering),  or, 
on  the  other  hand,  with  dumbness  and  aphonia. 

In  some  cases  of  Duchenne's  disease,  the  lips  are  not  af- 
fected ;  while,  in  others,  the  laryngeal  and  pharyngeal  mus- 
cles are  not  impaired  to  a  sufficient  degree  to  cause  any 
serious  impediment  to  their  normal  functions.  We  can 
the  better  understand  why  all  possible  varieties  and  degrees 
of  paralysis  may  exist  in  this  disease  when  we  consider  that, 
in  order  to  account  for  all  the  symptoms  present  in  a  fully 
developed  case,  the  facial,  spinal  accessory,  pneumogastric, 
and  Jiypo-glossal  nerves  must  be  simultaneously  diseased, 
or  subjected  to  extreme  pressure.  Should  the  facial  nerve 
escape,  the  lips  and  face  will  preserve  their  normal  power; 
if  the  spinal  accessory  nerve  be  unimpaired,  the  larynx  may 
escape,  provided  that  the  pneumogastric  nerve  remain  intact 
below  the  point  of  communication  between  these  two  nerves  ; 
if  the  hypo-glossal  nerve  be  normal,  the  symptoms  referable 
to  the  tongue  would  not  be  detected.  The  essential  lesion  of 
this  disease  seems  to  consist  of  a  degeneration  of  the  medulla 
oblongata  and  the  upper  portion  of  the  spinal  cord ;  hence 
the  nuclei  of  origin  of  the  facial,  spinal  accessory,  pneumo- 
gastric, and  hypo-glossal  nerves  are  liable  to  be  involved  to  a 
greater  or  less  extent  simultaneously.  Whether  the  view  of 
Leyden,  that  the  condition  is  one  of  myelitis,  will  be  sus- 
tained, is  still  uncertain,  but  that  the  condition  closely  re- 


GLOSSO-LABIO-LARYNGEAL  PARALYSIS.  281 

sembles  tliat  which  creates  the  spinal  paralysis  of  the  infant 
and  adult  seems  positive. 

The  previous  existence  of  the  early  manifestations  of  syph- 
ilis and  the  probable  activity  of  the  disease  in  the  system 
may  account  for  the  lesion  in  some  cases,  while  in  others  the 
rheumatic  diathesis,  mental  anxiety,  and  excessive  mental 
application, '  seem  to  have  acted  as  exciting  causes. 

The  general  paralysis  of  the  insane  often  first  manifests 
itself  in  a  peculiar  weakness  of  the  tongue  and  lips. 

The  tremor  of  paralytic  dementia  probably  first  makes  its 
appearance  in  the  facial  and  lingual  muscles.  It  consists  in 
non-rhythmical  contractions  of  small  muscles  or  of  fasciculi  of 
muscles,  which  are  either  present  in  the  quiescent  state  of  the 
features,  or  are  excited  by  emotion  or  by  the  performance 
of  a  voluntary  movement,  as  showing  the  tongue  or  teeth. 
Sometimes  innumerable  fine,  fibrillary  tremors  cover  the  face, 
while,  in  some  cases,  the  movements  are  coarser,  and  irregular 
enough  to  merit  the  term  choreic.  The  tongue  exhibits  both 
sets  of  tremors — the  very  fine  fibrillary  ones  and  the  large 
choreic  oscillations.  There  is,  also,  though  usually  at  a  later 
stage,  some  shriveling  or  atrophy  of  the  tongue.  I  quote 
from  a  late  article  of  Professor  E.  C.  Seguin,"  as  follows : 

''The  hands  are  tremulous,  usually  in  a  fine,  semi-rhyth- 
mical way.  This  trembling  is  sometimes  scarcely  visible, 
but  is  perceptible  as  a  delicate  parchment-like  fremitus  on 
holding  up  the  patient's  extended  fingers  between  ours.  In 
the  lower  extremities  the  tremulousness  is  not  apparent. 

''The  speech  is  affected  as  a  result  of  this  tremor,  and  as 
the  result  of  a  certain  want  of  coordination  in  the  muscles  of 
articulation.  Words  are  quickly  spoken,  with  some  syllables 
omitted  or  blurred,  or  with  a  terminal  syllable  left  off.  The 
articulate  sounds  which  are  produced  are  heard  as  vibratory 
or  tremulous,  and  the  speech  seems  thick.  Patients  semi-un- 
consciously  avoid  long  or  difficult  words  in  conversation,  and 

'  Such  cases  as  these  are  reported  in  the  admirable  description  of  this  complicated 
affection  by  my  colleague  and  friend  Professor  W.  A.  Hammond:  "Treatise  on  the 
Diseases  of  the  Nervous  System."     New  York:  D.  Appleton  &  Co.,  18*76. 

2  "Med.  Record,"  1881. 


THE   CRANIAL  NERVES. 


Fig.  105. — A  diagram  of  the  motor  points  of  the  face,  showing  the  position  of  tlie  electrodes 
during  electrization  of  special  miiscles  and  nerves.  Ilie  anode  is  supposed  to  be  placed 
in  the  mastoid  fossa,  and  the  cathode  upon  (he  part  indicated  in  the  diagram. 

1,  m.  orbicularis  palpebrarum  ;  2,  m.  pyramidalis  nasi ;  3,  m.  lev.  lab.  sup.  et  nasi ;  4,  m. 
ley.  lab.  sup.  propr. ;  5,  6,  m.  dilator  naris ;  1,  m.  zygomatic  major ;  8,  m.  orbicularis 
oris;  9,  n.  branch  for  levator  menti;  10,  m.  levator  menti ;  11,  m.  quadratus  menti; 
12,  m.  triangularis  menti;  13,  nerves — subcutaneous  of  neck;  14,  m.  sterno-hyoid ; 
15.  m.  omo-hyoid  ;  16,  m.  sterno-thyroid  ;  11,  n.  branch  for  platysma  ;  18,  m.  sterno- 
hyoid ;  19,  m.  omo-hyoid;  20,  21,  nerves  to  pectoral  muscles;  22,  m.  occipito- 
frontalis  (ant.  belly) ;  23,  m.  occipito-f rontalis  (post,  belly) ;  24,  m.  retrahens  and 
attollens  aurem;  25,  nerve — facial;  26,  m.  stylo-hyoid;  27,  m.  digastric;  28,  m. 
splenius  capitis ;  29,  nerve— external  branch  of  spinal  accessory ;  30,  m.  sterno- 
mastoid;  31,  m.  sterno-mastoid ;  32,  m.  levator  anguli  scapulae;  33,  nerve — phrenic; 
34,  nerve — posterior  thoracic ;  35,  m.  serratus  magnus ;  36,  nerves  of  the  axil- 
lary space. 


even  seek  roundabout  ways  of  expressing  their  meaning  by- 
shorter    words.      Besides    this    vibratory   tremulousness    in 


SPASM  AND  PARALYSIS   OF  THE  TONGUE.  283 

articulation,  there  is  an  imperfection  in  tlie  pronunciation 
of  words — long  words  especially.  Remedy  is  pronounced 
'remdy';  constitution,  '  constution ';  infallibility,  'infallaby.' 
The  last  syllable  may  be  badly  sounded,  or  even  omitted.  I 
have  known  this  characteristic  speech  to  be  the  only  well- 
marked  symptom,  and  to  be  followed  by  dementia,  exaltation, 
etc.  Occasionally,  a  patient  comes  to  us  complaining  of  this 
defective  articulation." 

Interference  with  the  free  action  of  the  hypo-glossal  nerve, 
when  not  associated  with  a  simultaneous  affection  of  other 
nerves,  may  result  in  the  production  of  spasm  or  paralysis. 

Spasm  of  the  tongue  may  be  perceived  in  connection  with 
the  spasmodic  diseases,  such  as  chorea,  epilepsy,  and  hys- 
teria ;  also,  as  a  result  of  slight  compression  or  irritation  of 
the  hypoglossal  nerve  from  meningeal  exudation;  while  a 
fibrillary  tremor  of  the  tongue  is  observed  in  progressive 
muscular  atrophy.  In  severe  types  of  facial  spasm,  and  in 
those  forms  of  disease  where  the  lingual  nerve  is  the  seat  of 
a  neuralgic  affection,  the  hypo-glossal  nerve  may  create  a 
type  of  clonic  spasm. 

Paralysis  of  the  tongue  is  usually  unilateral,  and  may 
be  the  result  of  cerebral  haemorrhage,  softening,  embolism, 
tumors,  or  the  progressive  paralysis  of  the  insane.  In  rare 
cases,  this  condition  has  occurred  from  injury  done  to  the 
nerve  from  the  removal  of  a  tumor  of  the  tongue  itself ;  while 
instances  have  been  reported  where  the  nerve  was  impaired 
by  pressure  upon  its  trunk,  either  at  the  base  of  the  brain,  or 
at  its  point  of  escape  from  the  anterior  condyloid  foramen. 


THE  SPINAL  CORD. 

ITS  ANATOMICAL   CONSTRUCTION,    FUNCTIONS,    AND 
CLINICAL  BEARINGS. 


THE  spi:n"al  coed. 


In  the  previous  lectures  of  this  winter's  course,  we  have 
considered  the  anatomy  of  the  brain,  and  the  nerves  which 
arise  from  it.  We  have  noted  the  general  points  in  the 
construction  of  each,  and  discussed  the  clinical  bearings 
of  the  individual  parts  which  have  successively  demanded 
our  attention.  It  now  remains  for  us  to  begin  the  study 
of  the  other  great  half  of  our  nervous  organism,  viz.,  the 
spinal  cord,  and  the  nerves  which  are  connected  with  it.  I 
shall  follow  the  same  general  plan,  in  treating  of  the  spinal 
cord  and  its  nerves,  as  I  have  pursued  in  the  early  part  of 
the  course,  viz.,  to  give  such  points  only  in  the  descriptive 
portion  as  shall  conduce  to  a  full  comprehension  of  the 
clinical  bearings  of  the  regions  under  discussion,  and  to  im- 
press upon  you  constantly  such  suggestions  of  practical  value 
as  the  theme  recalls  to  my  mind.  Should  the  anatomical  de- 
scription of  the  separate  parts  seem,  at  any  time^,^  incomplete, 
I  trust  to  omit  nothing  that  can  not  be  easily  supplied  from 
the  best  text-books  upon  anatomy ;  but  I  shall  fall  short  of 
my  proposed  task  if  I  fail  to  incorporate  such  points  as  shall 
assist  you  in  comprehending  many  of  the  new  terms  found 
scattered  throughout  the  more  advanced  treatises  upon  the 
anatomy  and  diseases  of  the  nervous  system. 

The  spinal  cord  comprises  that  part  of  our  central  nervous 
system  which  is  contained  within  the  canal  of  the  vertebral 
column.     It  may  be   said  to  begin  at  the  point  where  the 


288 


THE  SPINAL    CORD. 


fibers  of  the  anterior  pyramids  of  tlie  medualla  oblongata  be- 
gin to  decussate  (which  point  corresponds  to  the  upper  border 
of  the  atlas),  and  it  terminates  at  the  lower  border  of  the 
first  lumbar  vertebra.  It  may  then  be  stated  that  the  entire 
length  of  the  spinal  cord  varies  from  fifteen  to  eighteen 
inches  (since  it  depends  somewhat  upon  the  height  of  the  in- 


FiG.  106. —  Cervical  por- 
tion of  the  spinal  cord. 
(Hirschfcld.) 


Fig.  107. — Dorsal  por- 
tion of  the  spinal  cord. 
(Hirschfeld.) 


Fio.  108. — Inferior  por- 
tion of  the  spinal  cord, 
and  Cauda  equina. 
(Hirschfeld.) 


1,  antero-inferior  wall  of  the  fourth  ventricle ;  2,  superior  peduncle  of  the  cerebellum ; 
3,  middle  peduncle  of  the  cerebellum  ;  4,  inferior  peduncle  of  the  cerebellum  ;  5,  in- 
ferior portion  of  the  posterior  median  columns  of  the  cord  ;  6,  glosso-pharyngeal 
nerve ;  7,  pneumogastric  ;  8,  spinal  accessory  nerve  ;  9,  9,  9,  9,  dentated  ligament ; 
10, 10,  10,  10,  posterior  roots  of  the  spinal  nerves  ;  11,  11,  11,  11,  posterior  lateral 
groove;  12,  12,  12,  VI,  ganglia  of  the  posterior  roots  of  the  nerves  ;  13,  IS.aniei-ior 
roots  of  the  nerves  ;  14,  division  of  the  nei'ves  into  two  branches  ;  15,  lower  ex- 
tremity of  the  cord;  16,  16,  coccygeal  ligament;  17,  17,  cauda  equina;  I — VIII, 
cervical  nerves  ;  I,  II,  III,  IV — XII,  dorsal  nerves  ;  I,  II — V,  lumbar  ncj-vcs  ;  1 — V, 
sacral  nerves. 


dividual),  and  that  it  does  not  extend  throughout  the  entire 
length  of  the  spinal  canal.     Its  upper  end  is  continuous  with 


CERVICAL  AND  LUMBAR  ENLARGEMENTS.  289 

the  lower  part  of  the  medulla  oblongata  (which,  in  my  opin- 
ion, seems  more  properly  a  part  of  the  cord  than  of  the  brain), 
while  its  lower  end  terminates  in  a  slender  filament,  called  the 
*'filiim  terminale,"  which  descends  for  a  short  distance  into 
the  central  ligament. 

THE  GENERAL  CONSTRUCTION  OF  THE  CORD. 

The  spinal  cord  is  not  of  the  same  size  or  general  shape  in 
all  portions  of  its  length,  since  it  tapers  gradually  toward  its 
lower  extremity,  with  the  exception  of  presenting  two  local 
enlargements,  caUed  the  '' cermcaV^  and  "lumbar^'  enlarge- 
ments.^ The  former  of  these  extends  from  the  third  cervical 
to  the  first  dorsal  vertebra,  and  is  widest  from  side  to  side  ; 


Fig.  109. —  Transverse  section  of  the  spinal  cord  at  the  origin  of  the  fifth  pair '^  of  cervical 

nerves.     (Stilling.) 

In  this  fifTure,  the  white  substance  of  the  cord  is  represented  in  black,  to  show  more 
clearly  the  limits  of  the  gray  matter:  1,  1,  antero-lateral  columns;  2,  2,  posterior 
white  columns ;  3,  anterior  median  fissure  ;  4,  posterior  median  fissure ;  5,  white 
commissure ;  6,  gray  commissure ;  7,  central  canal ;  8,  9,  anterior  comua  of  gray 
matter;  10,  10,  group  of  large  multipolar  cells  ;  11,  11,  11,  anterior  roots  of  the 
spinal  nerves;  12,  posterior  cornua  of  gray  matter;  13,  posterior  roots  of  the 
spinal  nerves. 

while  the  latter  extends  from  the  lower  part  of  the  eleventh 
dorsal  to  the  lower  border  of  the  twelfth  dorsal  vertebra,  and 

'  These  enlargements  correspond  to  the  points  of  origin  of  the  main  nerves  of  the 
upper  and  lower  extremities. 

2  The  line  designated  by  Gubler.     See  page  183. 


290  THE  SPINAL   CORD. 

is  widest  from  before  backward.  When  viewed  exteriorly, 
the  cord  presents  five  fissures  and  four  columns^  which  are 
less  distinct  than  the  convolutions  of  the  cerebrum  ;  and,  on 
section  made  transversely  across  its  substance,  two  general 
subdivisions  can  be  made  out  by  the  naked  eye,  the  white  and 
the  gray  portions.  When  we  come  to  discuss  the  clinical 
points  pertaining  to  spinal  localization,  in  case  of  disease,  you 
will  then  realize  that  the  further  subdivisions  of  the  spinal 
cord,  which  I  shall  impress  upon  your  memories,  are  not 
based  alone  upon  the  results  of  enthusiastic  microscopy, 
but  are  the  grand  evidences  of  a  progress  in  this  direction 
which  the  earlier  anatomists  had  not  dreamed  of,  and  which 
are  the  foundation,  I  sincerely  believe,  of  accurate  and  posi- 
tive diagnosis  of  spinal  lesions  at  no  distant  date. 

The  general  exterior  of  the  spinal  cord  is  incompletely 
divided  into  two  symmetrical  lateral  halves^  by  the  so-called 
''antero-median  fissure"  and  the  " postero-median  fissure," 
which  do  not  cut  the  cord  entirely  in  half,  since  a  transverse 
commissure  exists,  called  the  '-^commissure  of  the  spinal 
cord.^^  Now,  this  point  is  worthy  of  your  careful  attention, 
since  it  indicates  a  clinical  fact,  viz.,  that  lesions  of  one  lateral 
half  of  the  cord  produce  symptoms  in  a  lateral  half  of  the 
body. 

Each  lateral  half  of  the  cord  has  three  fissures  of  its  own : 
the  "  antero-lateral  fissure,"  which  corresponds  to  the  points 
of  escape  of  the  anterior  roots  of  the  spinal  nerves  ;  the  *'  pos- 
tero-lateral  fissure,"  which  corresponds  to  the  points  of  at- 
tachment of  the  posterior  roots  of  the  spinal  nerves ;  and  the 
''postero-intermediary  fissure,"'  which  is  situated  on  the 
outer  side  of  the  postero-median  fissure,  which  helps  to  di- 
vide the  cord  into  its  two  lateral  halves.  The  first  two  of 
these  are  mere  traces  upon  the  surface  of  the  cord,  while  the 
last  is  most  apparent  in  the  cervical  region. 

As  demarcated  by  the  fissures  named  above,  the  spinal 
cord  presents  four  subdivisions  of  its  exterior  surface,  called 
respectively  the    ''anterior,"    "lateral,"    ''posterior,"    and 

^  Described  by  Sappey,  Hirechfeld,  and  others. 


FISSURES  AND    COLUMNS   OF  THE  CORD. 


291 


"  postero-median"  columns.'  These  are,  however,  of  less  im- 
portance, from  a  clinical  standpoint,  than  the  columns  named 
after  certain  special   investigators  in  this  line  of  science; 


f^^i- 


.y,^^,: 


Fig.  110. —  Transverse  section  of  the  spinal  cord  of  a  child  six  months  old,  at  the  middle  of 
the  lumbar  enlargement^  treated  with  potassio-cldoride  of  gold  and  nitrate  of  uranium  ; 
magnified  20  diameters.  By  means  of  these  reagents,  the  direction  of  the  fibers  in  the 
gray  substance  is  rendered  unumally  distinct.     (Gerlach.) 

«,  anterior  columns ;  6,  posterior  columns  ;  c,  lateral  columns ;  d,  anterior  roots  ;  e,  poste- 
rior roots ;  /,  anterior  white  commissure,  in  communication  with  the  fasciculi  of  the 
anterior  cornua  and  the  anterior  columns ;  g,  central  canal  with  its  epithelium ;  Ji, 
surrounding  connective  substance  of  the  central  canal ;  i,  transverse  fasciculi  of  the 
gray  commissure  in  front  ol"  the  central  canal ;  k,  transverse  fasciculi  of  the  gray 
commissure  behind  the  central  canal ;  I,  transverse  section  of  the  two  central  veins ; 
m,  anterior  cornua ;  n,  great  lateral  cellular  layer  of  the  anterior  cornua ;  o,  lesser 
anterior  cellular  layer;  p,  smallest  median  cellular  layer;  q,  posterior  cornua;  r, 
ascending  fasciculi  in  the  posterior  cornua ;  s,  substantia  gelatinosa. 

which  can  better  be  demonstrated  by  a  reference  to  the  cuts 
showing  the  transverse  section  of  the  spinal  cord.' 

The  spinal  cord  gives  off  thirty-one  pairs  of  nerves^  called 

^  Some  anatomists  include  the  lateral  with  the  anterior  column,  under  the  name  of  the 
"  antero-lateral  column,"  thus  taking  in  about  two  thirds  of  the  entire  lateral  half  of  the 
cord. 

^  See  cut  on  page  298  of  this  volume,  and  colored  plate  (after  Hammond), 


292  THE  SPINAL   CORD. 

''spinal  nerves,"  in  contradistinction  to  those  of  cranial 
origin,  which  we  have  already  considered.  Each  spinal  nerve 
arises  by  two  roots,  which  spring  respectively  from  two  of  the 
fissures  of  the  lateral  halves  of  the  cord,  as  has  been  men- 
tioned ;  but  these  two  roots  soon  join  with  each  other  to  form 
the  nerve,  before  it  escapes  from  the  spinal  canal,  to  be  dis- 
tributed to  the  regions  which  it  is  destined  to  supply. 

THE  MEMBRAlfES   OF  THE   SPINAL  CORD. 

As  was  the  case  with  the  encephalon,  the  spinal  cord  is  in- 
vested from  within  outward  by  a  membrane  of  nutrition^  the 
pia  mater  ;  a  membrane  of  lubrication^  the  arachnoid  ;  and, 
finally,  a  membrane  of  protection^  the  dura  mater.  These 
three  coverings  differ  in  some  respects  from  those  covering 
the  brain,  but  the  differences  have  little  if  anything  to  do 
with  the  clinical  aspects  of  the  spinal  cord,  and  they  can  be 
ascertained,  if  you  desire  to  know  them,  by  reference  to  any 
text-book  on  descriptive  anatomy. 

THE   CEREBRO-SPINAL   FLUID. 

As  mentioned  in  connection  with  the  ventricular  cavities 
of  the  brain,  the  spinal  cord  is  immersed,  as  it  were,  in  a 
fluid,  the  ''  cerebrospinal  Jluid,'^^  which  has  free  entrance  to 
and  egress  from  the  ventricles  of  the  encephalon,  since  its 
function  is  to  regulate  and  equalize  the  pressure '  upon  the 
nerve  centers,  when  the  blood  supply  suffers  variations,  as 
it  does  during  respiration,  in  sleep,  and  in  certain  diseased 
conditions.  This  accounts  for  the  fact  that  pressure  made 
upon  a  ''spina  bifida" — a  tumor  containing  this  fluid  pro- 
truding through  an  opening  due  to  a  congenital  absence  of 
the  spinous  processes  of  the  vertebrse — often  creates  brain 
symptoms,  if  sufficient  to  create  excessive  intra-ventricular 
pressure. 

The  greater  part  of  this  fluid  is  contained  in  what  is  known 

'  Hiltou  considers  this  fluid  as  analogous,  in  respect  to  its  function,  to  the  elastic  cap- 
sule of  the  various  solid  viscera.     "  Rest  and  Pain,"  London,  1876. 


THE  CEREBROSPINAL  FLUID.  293 

as  the  sub-ai^acJinoidean  space,  which  is  situated  outside  of 
the  cavity  of  the  arachnoid,  between  its  inner  layer  and  the 
pia  mater  of  the  cord.  Its  quantity  was  estimated  by  Ma- 
gendie  as  about  two  fluidounces  in  the  human  subject ;  but 
a  somewhat  larger  amount  can  be  obtained  by  making  an 
opening  in  the  lumbar  region  and  a  counter-opening  in  the 
region  of  the  head,  so  as  to  allow  of  the  influence  of  atmos- 
pheric pressure  in  forcing  its  escape  outward/ 

This  fluid  may  be  drawn  out  of  the  spinal  canal  of  a  living 
animal,  either  by  means  of  a  simple  trocar  or  a  trocar  at- 
tached to  a  suction  tube.  In  the  former  method,  no  apparent 
influence  of  a  detrimental  character  seems  to  follow  a  mod- 
erate escape  ;  but,  when  a  suction  force  is  used  to  still  fur- 
ther draw  olf  the  fluid,  the  animal  becomes  enfeebled  and 
subsequently  affected  with  symptoms  of  motor  paralysis. 
The  cerebro-spinal  fluid  is  rapidly  reproduced  after  its  with- 
drawal, and  is  probably  secreted  by  the  pia  mater.  The 
fact  that  an  increase  of  the  intra-cerebral  pressure  will  result 
in  coma,  if  sufficiently  intensified,  is  shown,  in  a  clinical  way, 
upon  the  human  subject,  by  compression  of  a  spina  bifida  ; 
and  the  same  result  was  proved  by  Magendie,  who  injected 
water  into  the  sub-arachnoidean  space  of  animals,  and  thus 
artificially  induced  a  state  of  profound  coma.  The  point  of 
communication  between  the  sub-arachnoidean  space  of  the 
spinal  canal  and  the  ventricular  cavities  of  the  brain  is  situ- 
ated in  the  fourth  mntricle  ;  hence,  the  fluid  has  to  pass  up- 
ward, through  the  aqueduct  of  Sylvius,  to  reach  the  third 
ventricle,  and  through  the  foramina  of  Monro,  to  enter  the 
two  lateral  ventricles  of  the  cerebrum.  Hilton ""  claims  that 
the  basilar  process  of  the  occipital  bone,  which  is  the  seat  of 
some  of  the  more  important  parts  of  the  encephalon,  is  not  in 
actual  contact  with  the  adjacent  brain,  but  has  a  layer  of  the 
cerebro-spinal  fluid  interposed  as  a  water-bed  to  protect  the 
parts  from  injury  from  any  form  of  concussion,  and  a  similar 
condition  probably  exists  in  other  parts. 

^  A.  Flint,  Jr.,  op.  cit.  ^  Op.  cii. 

21 


294  THE  SPINAL   COED. 

APPEARANCE   OF   A  TRANSVERSE   SECTION   OF  THE   SPINAL   CORD. 

The  arrangement  of  the  gray  and  white  substance  of  the 
spinal  cord  is  seen  only  on  a  transverse  section.  In  order  to 
properly  appreciate  the  special  points  in  the  construction  of 
these  two  portions,  several  transverse  sections  must  be  made 
at  different  heights  in  the  cord,  since  the  relative  proportion 
of  the  gray  and  white  substance  differs  in  the  cervical,  dorsal, 
and  lumbar  regions.  The  regions  usually  selected  for  these 
transverse  sections  are  the  upper  cervical  portion,  the  center 
of  the  cervical  enlargement,  the  center  of  the  dorsal  region, 
the  lumbar  enlargement,  and  the  terminal  portion  of  the 
cord.  In  the  cervical  region,  the  white  substance  is  the 
most  abundant ;  in  the  dorsal  region,  the  gray  matter  is 
relatively  smaller  than  at  any  other  point ;  while,  in  the 
lumbar  enlargement,  the  gray  matter  is  the  most  extensively 
developed. 

When  we  view  the  appearance  of  any  portion  of  the  spinal 
cord  on  transverse  section,  we  will  perceive  that  the  gray 
matter  is  arranged  in  the  same  general  way  in  all  of  its  differ- 
ent regions.  This  has  been  compared  to  the  capital  letter 
"H,"  since  its  two  lateral  halves  are  connected  together  by 
a  transverse  band,  •'  the  transverse  commissure  of  the  gray 
substance."  Each  lateral  half  of  the  gray  substance  is 
crescentlc  in  form,  thus  presenting  an  anterior  and  a  pos- 
terior projection,  termed  the  anterior  and  posterior  horns,' 

}  The  anterior  horns,  or  cornua,  arc  studded  with  large  characteristic  cells,  which  are 
unipolar  or  multipolar.  Certain  of  these  cells  are  possessed  of  a  peculiar  process,  which 
differs  from  its  companions  in  not  branching,  and  in  increasing  in  size  as  it  passes  away 
from  the  body  of  the  ceil.  This  is  known  as  the  "  axis  cylinder  process,"  and  it  is  claimed 
that  it  becomes  clothed  with  myeline  and  is  directly  continuous  with  the  axis  cylinder  of  a 
motor  nerve.  We  owe  the  discovery  of  this  process  in  the  human  being  to  Deiters  ("  Un- 
tersuehungen  Uber  Gchirn  u.  Riickenmark,"  1868),  who  asserted  that  it  was  also  to  be 
found  appended  to  all  central  nerve  cells;  although,  in  18Y4,  R.  Wagner  ("Ilandworter- 
buch  ")  had  observed  a  similar  prolongation,  sometimes  two,  in  the  central  nervous  organs 
of  the  torpedo,  and  Remak  ("Deutsche  Klinik,"  1854,  Nro.  27)  had,  in  1854,  described 
the  same  peculiarity  of  structure  in  the  anterior  horn  cells  of  the  spinal  cord  in  the  ox. 
Deiters  has  been  confirmed  by  a  number  of  observers,  among  others  by  Max  Schultze, 
Jolly,  Gcrlach,  Arnold,  KoUiker,  Arndt,  Koschennikoff  (see  Ilenle,  •' Norvcnlehre,"  1879, 
^  20).  These  cells  are  distributed  in  groups,  which  arc  differently  situated  in  different 
regions.     (L.  C.  Gray,  "Annals  of  Anat,  and  Surg.  Soc,"  Oct.,  1880.) 


APPEARANCE  OF  A    TRANSVERSE  SECTION. 


295 


tlie  former  of  whicli  is  broad  and  blunted,  and  does  not 
reach  the  surface  of  the  cord,  while  the  latter  is  thinner 
and  more  pointed,  and  approaches  the  exterior  surface  near 
the  point  of  attachment  of  the  posterior  roots  of  the  spinal 
nerves. 

The  white  substance  consists  of  the  following  component 
structures :  1,  nerve  fibers ;  2,  blood-vessels ;  and  3,  connec- 
tive-tissue elements.  The  gray  matter,  called  also  the  ''  vesic- 
ular neurine,"  consists,  1,  of  nerve  cells  of  variable  shapes  and 
sizes ;  2,  nerve  fibers ;  3,  blood-vessels ;  and  4,  connective-tis- 
sue elements.  In  the  w^hite  substance,  the  nerve  fibers  are 
variable  in  point  of  size,  and  have  a  medullary  sheath,  but  no 
investing  membrane.  In  the  gray  matter  the  nerve  fibers  are 
small,  and,  in  the  posterior  horns,  form  plexuses.  The  nerve 
cells  are  large  and  multipolar  in  the  anterior  horns,  and 
smaller  in  the  posterior  horns. 


Fig.  111. — Section  of  the  cord  below  the  Fig.  \\2.— Section  of  the  cervical  enlccrgc- 

medulla  oblongata.    (Sappey.)  mcnt  of  the  cord.     (Sappey.) 

Fig.  111. — 1,  anterior  median  fissure;  2,  posterior  median  fissure;  3,  gray  commissure, 
much  thicker  here  than  lower  down ;  4,  white  commissure  formed  by  the  decussa- 
tion of  the  anterior  columns ;  5,  anterior  cornu  ;  6,  posterior  cornu  ;    7,  lateral  cornu. 

Fig.  112. — 1,  anterior  fissure ;  2,  posterior  fissure  :  3,  3,  anterior  columns  of  most  authors; 
4,  4,  lateral  columns  (these  columns  in  reality  pass  beyond  the  anterior  cornua,  and 
the  anterior  columns  occupy  less  space  than  is  here  allowed  them) ;  5,  posterior  col- 
umns ;  posterior  commissure  (here  very  narrow  ) ;  7,  reticulated  arrangement  of  the 
gray  and  white  matter  at  the  junction  of  the  two  cornua ;  8,  anterior  cornu ;  8,  ante- 
rior cornu,  in  which  the  multipolar  cells  are  distributed  into  three  principal  groups;  9, 
posterior  cornu  ;  10,  fifth  pair  of  cervical  nerves. 


Passing  through  the  center  of  the  gray  commissure,  and 
extending  for  the  greater  portion  of  the  length  of  the  cord, 


296 


THE  SPINAL    CORD. 


may  be  seen  a  small  canal — tlie  central  canal  of  the  spinal 
cord.^  That  portion  of  the  gray  commissure  which  lies  in 
front  of  this  canal  may  be  called  the  "anterior  gray  commis- 
sure," while  the  portion  which  lies  behind  it  is  called  the 


1^3 


Fig.  113. — Section  from  the  dorsal  region  Fig.  114. — Section  of  the  lumbar  enlarge- 

of  the  cord.     (Sappey.)  ment  of  the  cord.     (Sappey.) 

Fig.  113. — 1,  anterior  fissure;  2,  posterior  fissure  ;  3,  anterior  column  situated  within  the 
corresponding  cornu,  and  decussating  in  the  median  line  with  the  column  of  the  op- 
posite side ;  4,  4,  lateral  column  reaching  to  the  anterior  column,  but  separated 
from  it  by  no  distinct  line  of  demarkation  ;  5,  posterior  column ;  6,  7,  section  of  the 
columns  of  Clarke,  situated  at  the  two  extremities  of  the  gray  commissure,  at  the 
junction  of  the  anterior  and  posterior  cornua,  and  9ontaining  large  multipolar  cells  ; 
8,  anterior  cornu;  9,  posterior  cornu;  10,  posterior  root  of  dorsal  nerves. 

Fig.  114. — 1,  anterior  fissure  ;  2,  posterior  fissure  ;  3,  3,  anterior  columns  of  most  authors; 
4,  4,  lateral  columns  of  most  authors  ;  5,  posterior  column  ;  6,  gray  commissure  and 
central  canal,  and,  to  the  right  and  left  of  the  latter,  the  orifices  of  two  longitudinal 
veins ;  7,  reticulated  arrangement  of  white  and  gray  matter ;  8,  anterior  cornu  ;  9, 
posterior  cornu  ;  1 0,  posterior  root  of  the  lumbar  nerves. 


"posterior  gray  commissure."     In  front  of  the  gray  commis- 
sure a  band  of  white  nerve  substance  connects  the  two  lat-  | 
eral  halves  of  the  cord,  to  which  the  term  "anterior  white  " 
commissure  "  is  applied. 

We  can  see,  by  such  a  transverse  section,  that  the  poste- 
rior horns  divide  the  lateral  half  of  the  cord  into  two  great  | 
subdivisions,  the  one  lying  anterior  to  it  being  called  the 
antero-lateral  column^  and  that  posterior  to  it  being  known 
as  the  posterior  column.  In  the  colored  plate,  which  is  taken 
from  the  admirable  work  of  my  friend  and  colleague  Profes- 


'  This  canal  i8  continuous,  above,  with  the /o?/r/A  ventricle  of  the  brain  ;  and  the  aque- 
duct of  Sylvius  is  considered  by  some  anatomists  as  a  continuation  of  it  above  the  fourth 
ventricle. 


Fig.  115. — Diagram  illustrating  the  relations  of  the  nerve-fiber  tracts  in  the  spinal  cord. 
The  section  is  supposed  to  be  taken  transversely  through  the  lower  part  of  the 
cervical  enlargement  (slightly  modified  from  Flechsig  by  Hammond) : 


Anterior  Median  Fissure. 

Posterior  Median  Fissure. 

Intermediate  Fissure. 

Anterior  Gray  Cornu. 

Posterior  Gray  Cornu. 

Gray  Commissure,  with  Central  Canal. 

Uncrossed  Pyramidal  Tract  (Flechsig),  or  Column  of  Tiirck. 

Fundamental  Part  of  the  Anterior  Column  (Anterior  Koot-Zones  of  Charcot  and  liis 

pupils). 
Anterior  Part  of  Lateral  Column. 
Crossed  Pyramidal  Tract  of  Lateral  Column. 
Direct  Tract  from  Lateral  Column  to  Cerebellum. 
Column  of  Burdach,  Posterior  Root-Zones  of  Charcot  and  his  pupils. 
Column  of  Goll. 


The  posterior  columns  of  descriptive  anatomy  include  the  fields  M  and  N  extending  on 
the  surface  firom  B  to  E.  The  antero-lateral  columns  extend  on  the  surface  from 
R  to  A.  Their  anterior  division  includes  the  fields  G  and  II;  their  lateral  division, 
the  fields  K,  L,  and    I. 


CLINICAL  SUBDIVISIONS  OF  THE  COED.  297 

sor  Hammond,  it  will  be,  however,  perceived  that  the  simple 
anatomical  divisions  of  the  cord  have  been  modified  by  patho- 
logical researches,  so  that  certain  special  regions  are  now  des- 
ignated, and  some  are  named  after  the  investigator  who  first 
discovered  their  function.  Thus,  to-day,  we  more  commonly 
read  of  the  columns  of  Goll,  of  Tiirck,  of  Burdach,  and  of  the 
'^anterior  root  zone"  and  the  ''posterior  root  zone,"  than 
of  the  anatomical  terms  with  which  you  are  doubtless  more 
familiar.  This  is  not  without  benefit  to  those  who  expect  to 
master  the  mechanism  of  the  symptomatology  of  the  more 
important  types  of  spinal  diseases,  although  it  may  for  a 
while  tend  to  confuse  you  ;  since  the  situation  of  lesions  can 
be  thus  more  simply  expressed  than  in  attempts  to  use  terms 
which  are  inadequate  to  convey  the  idea.  The  anatomical 
subdivisions  of  the  cord  are  fast  becoming  obsolete  terms  with 
the  alienist,  since  they  are  based  upon  a  purely  structural 
foundation,  irrespective  of  the  physiological  properties  of  the 
different  parts. 

A  few  words  of  explanation  of  this  selected  plate '  will 
assist  you,  I  trust,  in  mastering  these  new  terms  so  readily 
that  you  will  be  able  to  follow  my  subsequent  remarks  with 
as  much  ease  as  if  you  had  not  been  so  long  accustomed  to 
the  terms  which  will  be,  to  a  great  extent,  discarded.  You 
will  perceive  that  the  gray  matter  is  shown  with  its  two  ante- 
rior and  two  posterior  horns  (D  and  E) ;  and  also  the  antero- 
median and  postero-median  fissures,  separating  the  cord  into 
two  lateral  halves.  In  the  anterior  part,  lying  on  each  side  of 
the  antero-median  fissure,  are  seen  the  "columns  of  Tiirck" 
(G),  which  are  also  called  the  "direct  pyramidal  columns," 
from  the  course  of  the  nerve  fibers  which  form  them.  On 
either  side  of  these  columns,  extending  backward  toward  the 
line  of  the  transverse  commissure  of  the  cord,  are  the  two  re- 
gions (H)  which,  from  their  relation  to  the  anterior  roots,  are 
called  the  "anterior  root  zones."  ^  As  we  pass  still  farther 
backward,  we  next  meet  the  two  lateral  columns  (I),  which, 
as  you  will  see,  are  limited  behind  by  the  posterior  horns  of 

'  See  Fig.  115.  *  Called  also  the  ^'- anterior  fundamental  column.'''' 


298 


IHE  SPINAL   CORD. 


gray  matter.  Thus  the  antero-lateral  column  of  the  anato- 
mist has  already  been  split  up  into  three  distinct  i^ortions, 
each  of  which  is  specially  named.' 

This  lateral  column  is  sometimes  further  subdivided  into 
the  "direct  cerebellar  column"  and  the  ''crossed  pyramidal 
column,"  as  shown  in  the  colored  plate  taken  from  Ham- 
mond, and  also  in  an  admirable  schematic  drawing  which  I 
have  copied  from  Seguin.'* 

Behind,  and  adjoining  the  posterior  horns  of  gray  matter, 
you  will  see  two  greenish-colored  portions  (M),  the  posterior 
root  zones,  or  the  "  columns  of  Burdach"  ;  while  upon  either 
side  of  the  postero-median  fissure  lie  the  "  columns  of  GoU  " 
(N),  which  are  colored  pink. 

P 


Fig.  116. — Transverse  section  of  the  spinal  cord  and  center.     (Seguin.) 

A,  anterioi'  median  fissure ;  P,  posterior  median  septum  :  1,  columns  of  Goll ;  2,  columns 
of  Burdach ;  3,  direct  cerebellar  column ;  4,  crossed  pyramidal  column ;  5,  lateral 
column ;  6,  anterior  fundamental  column ;  7,  direct  pyramidal  column  (column  of 
Tiirck) ;  8,  posterior  gray  horns ;  9,  anterior  gray  horns.  Stippled  part — gray  mat- 
ter.     Shaded  part — aesthesodic  system.     Unshaded  part— kinesodic  system. 

We  can,  again,  thus  perceive  that  the  "posterior  column  " 
of  the  simpler  classification,  with  which  you  are  familiar, 
comprises  the  "  columns  of  Goll  and  of  Burdach." 

*  See  researches  of  Flcchsig,  of  Leipsic,  regarding  the  course  of  fibers  in  the  medulla 
oblongata  and  spinal  cord. 
-  "Medical  Record,"  1878. 


PATHS  OF  CONDUCTION  IN  THE  SPINAL   CORD.        299 
FUXCTIOXS   or   THE   SPII^AL   CORD. 

Now,  the  questions  may  naturally  arise  to  your  minds : 
Why  is  such  a  digression  from  previously  accepted  terms  so 
universally  used,  in  preference  to  those  more  familiar  and, 
possibly,  simpler  terms  of  nomenclature?  Why  should  the 
columns  of  Tiirck,  Goll,  and  Burdach  be  separated  from  each 
other  when  no  anatomical  line  of  division  seems  to  have  been 
created  ?  Is  the  arrangement  not  a  strained  attempt  to  mys- 
tify and  confuse  the  medical  student,  and  does  a  sufficient 
ground  exist  for  so  great  a  departure  from  previous  methods 
of  description  ?  In  reply  to  such  anticipated  questions — and 
they  have  been  asked  of  me  many  times — I  would  respectfully 
draw  your  attention  to  such  points  in  the  physiology  and 
pathology  of  the  spinal  cord  as  will  help  to  show  you  the 
necessity  which  existed  for  such  modifications  of  previously 
familiar  terms,  as  well  as  the  advantages  which  are  gained 
by  those  subdivisions  of  the  cord  which  are  now  household 
words  to  the  specialist  on  nervous  diseases. 

I  would  first  call  your  attention  to  the  fact  that  the  spinal 
cord  is  an  organ  of  conduction.  The  motor  impulses,  which 
affect  the  muscles  of  the  different  parts  of  the  body,  are  un- 
questionably transmitted  through  it  from  the  brain  to  the 
part  destined  to  be  acted  upon  ;  hence  we  know  that  centrifu- 
gal impulses  need  not  be  created  in  the  cord  itself,  but  may 
be  transmitted  from  the  brain.  We  see  this  illustrated  in  the 
hemiplegias  of  cerebral  origin.  We  also  have  equally  positive 
proof  that  certain  sensory  impressions  are  conducted  by 
means  of  the  spinal  cord  to  the  brain  ;  hence,  centripetal  im- 
pulses or  impressions  must  pass  upward  in  some  instances. 
We  see  this  fact  verified  in  the  hemi-ansesthesia  which  often 
accompanies  motor  paralysis  of  cerebral  origin.  Now,  it  can 
be  stated,  with  an  approach  to  accuracy,  that  it  is  as  certainly 
proved  that  the  motor  impulses  travel  along  the  anterior  half 
of  the  spinal  cord,  while  the  path  of  sensory  impressions!^  in- 
timately associated  with  the  posterior  half  of  the  spinal  cord.' 

^  This  statement  is  only  approximately  correct,  as  will  be  shown  in  the  text  of  subse- 
quent pages. 


300  THE  SPIRAL   CORD. 

If  you  will  direct  your  attention,  in  tlie  second  place,  to 
the  fact  that  the  motor  fibers  found  in  the  anterior  roots  do 
not  decussate  ^  until  they  reach  the  medulla  oblongata,  while 
the  sensory  fibers  found  in  the  posterior  roots  ascend  in  the 
columns  of  Burdach  for  a  short  distance  only,  when  they 
pass  into  the  gray  matter  of  the  opj^osite  half  of  the  cord,  we 
can  understand  why  any  interference  with  the  motor  fibers  (if 
below  the  medulla)  produces  paralysis  on  the  corresponding 
slde^  while  any  interference  with  the  sensory  roots  produces 
ancBsthesia  on  the  opposite  side  of  the  body. 

Again,  the  antero-lateral  columns  of  the  cord,  which  com- 
prise the  portion  situated  between  the  antero-median  fissure 
and  the  point  of  attachment  of  the  posterior  roots  of  the 
spinal  nerves,  are  not  sensible  to  any  form  of  direct  irritation." 
This  is  a  point  of  some  clinical  interest,  since,  in  certain  mor- 
bid conditions,  a  marked  change  in  this  respect  occurs,  and 
the  inexcitable  portions  may  then  give  rise  to  abnormal  sensa- 
tions and  to  spasm  of  the  muscles.  If  these  columns  be 
divided,  voluntary  motion  is  lost  in  all  the  parts  below  the 
point  of  section ;  while,  if  aU  the  other  portions  of  the  cord 
be  divided,  leaving  the  antero-lateral  columns  intact,  the 
power  of  voluntary  motion  remains.  The  columns  of  Tiirck 
and  the  crossed  pyramidal  columns  are  colored  alike  in  the 
plate.  This  indicates  a  probable  similarity  of  function  be- 
tween these  two  subdivisions  of  the  cord. 

The  gray  matter  of  the  cord  seems  to  be  most  intimately 
associated  with  the  transmission  of  sensory  impressions  to 
the  brain,  and  that  portion  which  lies  in  close  relation  to  the 
central  canal  of  the  cord  is  apparently  the  most  important 
of  the  transmittory  apparatus.'  If  the  entire  gray  substance 
of  the  cord  be  divided,  little  or  no  injury  being  done  to  the 

^  As  regards  this  point,  Brown-S6quai'd  says :  "  In  animals,  there  seems  to  be  in  the 
spinal  cord  itself  a  decussation  of  a  few  of  the  motor  conductors."  I  do  not  think,  how- 
ever, that  such  a  decussation  can,  as  yet,  be  verified  in  man.  If  such  decussation  docs 
exist,  it  is  present  only  in  the  cervical  region,  and  not  in  the  dorsal  and  lumbar  regions. 

^  The  experiments  of  Vulpian  seem  to  prove  that  the  internal  portion  of  the  anterior 
column  docs  exhibit  a  trace  of  excitability  in  the  normal  state. 

*  The  experiments  of  Brown-Sequard  seem  to  warrant  this  conclusion.  Very  little 
gray  matter  may,  therefore,  suffice  to  convey  all  sensory  impressions. 


I 


FUNCTIONS  OF  THE  SPINAL   CORD,  30I 

white  substance,  all  power  of  perceiving  sensations  seems  to 
be  destroyed  below  the  point  of  section.  In  addition  to  this 
function,  the  gray  matter  of  the  cord  seems  to  exert  a  con- 
trolling influence  upon  the  nutrition  of  muscles  and  other 
tissues,  since,  w^hen  the  anterior  portion  becomes  the  seat  of 
disease,  the  muscles  often  undergo  atrophy,  and  occasionally 
joint  diseases  develop.  This  so-called  "trophic function^^  \^ 
not  yet  thoroughly  understood.  Finally,  the  gray  matter  of 
the  cord  is  known  to  embrace  several  centers,  the  two  most 
important  of  which  are  the  cilio-spinal  center  and  the  genito- 
urinary center.  The  former  of  these  is  situated  in  the  cervi- 
cal region,  at  its  lowest  part,'  and  exerts  an  influence  upon 
the  pupil  of  the  eye  and  the  skin  of  the  face  and  neck ; 
hence  it  is  often  a  valuable  guide  to  determine  the  height  of 
a  lesion  in  the  spinal  cord,  since  the  pupils  show  changes 
when  it  is  involved  that  are  of  value  to  the  diagnostician. 
The  latter  center  (genito-urinary)  is  situated  in  the  dorso- 
lumbar  portion  of  the  cord,  and  often  creates  symptoms, 
when  disease  of  the  cord  exists,  referable  to  the  bladder  and 
genital  organs.  Certain  smaller  centers,  having  a  vaso-motor 
function,  are  described  by  some  authors  ;  but  their  situation 
and  special  functions  are  either  unknown  or  of  little  practical 
utility  in  diagnosis,  while  the  physiological  centers  of  the 
cord  are,  as  yet,  a  matter  deserving  further  investigation  be- 
fore any  positive  statements  can  be  made  concerning  them. 

In  the  posterior  column  of  the  cord,  comprising  the  col- 
umns of  Goll  and  of  Burdach,  there  exists  a  certain  amount 
of  white  substance,  whose  function  seems  to  be  chiefly  to  act 
as  commissural  fibers  between  certain  portions  of  the  spinal 

^  The  researches  of  Waller,  Budge,  and  Brown  .Sequard  would  indicate  the  limits  of 
this  center  between  the  fifth  cervical  and  second  dorsal  vertebrae.  It  exists  in  each  lat- 
eral half  of  the  cord.  It  presides  over  the  vaso-motor  nerves  for  the  vessels  of  the  cor- 
responding eye  and  side  of  the  face  and  neck.  Vulpian  places  its  limits  as  low  as  the 
fourth  dorsal,  and  Claude  Bernard  as  low  as  the  seventh  dorsal,  while  Schiff  carries  its 
limits  as  high  as  the  medulla  itself. 

Vulpian's  conclusions  indicate  the  gray  matter  of  the  cord  as  positivcl;/  incapable  of 
cxcitabilitii ;  but  he  attributes  slight  excitability  to  the  anterior  fasciculi  of  the  cord  and 
great  excitability  to  the  posterior  columns.  In  these  deductions,  he  differs  somewhat 
from  the  results  of  Chauveau,  made,  in  1861,  upon  the  domestic  animals. 


302  THE  SPINAL   CORD. 

cord.  This  portion  has  also  some  important  relation  to  the 
power  of  coordination '  of  muscular  movement,  since  disease 
of  this  region  of  the  cord  is  followed  or  accompanied  by  dis- 
orders of  motion,  called  ataxic  symptoms,  which  are  not  due 
to  paralysis. 

Like  the  cerebrum,  the  spinal  cord  has  the  inherent  power 
of  presiding  over  certain  muscular  acts.  It  is  now  quite  con- 
clusively proven  that  the  automatic  acts  of  walking,  standing, 
swimming,  and,  to  some  extent,  playing  upon  musical  instru- 
ments, dressing,  etc.,  are  largely  controlled  by  the  spinal  cord 
alone.  It  is  unquestioned  that  certain  of  these  acts  can  be 
made  so  mechanical  that  the  spinal  cord  is  slowly  and  pain- 
fully educated  to  perform  them  without  any  aid  from  the 
cerebrum.  It  is  not  generally  accepted,  however,  that  the 
gray  matter  of  the  cord  has  anything  to  do  with  the  attribute 
of  consciousness. 

FIBERS   OF   THE    SPII^AL   CORD. 

There  are  probably  three  varieties  of  fibers  within  the  sub- 
stance of  the  spinal  cord,  viz.,  motor  fibers,  sensory  fibers, 
and  commissural  fibers.  Each  of  these  has  been  already  men- 
tioned, and  some  points  of  general  interest  pertaining  to  their 
situation  and  function  have  been  given ;  but  there  are  still 
some  points  which  must  be  understood  before  we  are  able  to 
intelligently  discuss  the  symptoms  of  spinal  affections. 

The  motor  fibers  are  contained  in  the  anterior  roots  of  the 
spinal  nerves  and  escape  from  the  substance  of  the  cord  in 
the  region  of  the  anterior  horns  of  gray  matter.  If  we  trace 
them  from  the  nerve  trunk  toward  the  center  of  the  cord,  we 
shall  find  that  they  penetrate  the  anterior  horns,  and  are  in 
immediate  connection  with  the  prolongations  of  the  motor 
cells  of  that  portion  of  the  gi'ay  matter.  Certain  motor  fibers 
can  be  also  traced  toward  the  brain,  passing  upward  in  the  an- 
terior portion  of  the  white  substance  of  the  cord,  while  pro- 
longations of  the  motor  cells  of  the  gray  matter  are  also  found 

'  The  cerebellum  has  also  much  to  do  with  the  coordination  of  muscular  movements. 
The  reader  is,  therefore,  referred  to  page  64  of  this  volume. 


VARIETIES   OF  FIBERS  IK  THE   CORD. 


303 


'iG.  117. — Nerve  cell  from  the  anterior  cornua  of  the  sphial  cord  of  the  calf  macerated 

for  a  short  time  in  iodized  serum  ;  magnified  600  diameters.     (Schultzc.) 

a,  a,  axis-cylinder  prolongation  ;  h,  b,  6,  6,  branching  prolongations. 


304  THE  SPINAL   CORD. 

to  be  associated  with  these  fibers,  which  ascend  to  the  brain  in 
the  white  substance.  K'ow,  this  connection  between  the  motor 
fibers  and  the  nerve  cells,  and  the  second  connection  of  the 
cells  with  fibers  going  to  the  brain,  would  seem  to  suggest  the 
pleasing  hypothesis  that  the  motor  impulses  are  sent  first  from 
the  brain  to  the  cells  of  the  cord,  and  from  them,  through  the 
motor  nerves,  to  the  muscles ;  and  that,  when  the  cord  is 
taught  to  perform  certain  automatic  acts  without  the  interven- 
tion of  cerebral  action,  these  cells  themselves  are  the  exciting 
organs  of  the  motor  impulses  (since  they  are  the  elements 
which  are  most  probably  concerned  in  the  reflex  movements 
of  the  spinal  cord).  We  know  that  the  legs  of  a  frog  can  be 
made  to  perform  muscular  movements  after  the  head  has  been 
taken  off,  by  simply  stimulating  the  sensory  nerves  ;  and  we 
see  the  same  reflex  movements  occurring  in  paralyzed  limbs, 
which  are  out  of  the  voluntary  control  of  the  brain.  To  ex- 
plain these  phenomena,  we  must  believe  that  the  motor  cells 
of  the  cord  are  capable,  when  called  upon,  of  performing  many 
muscular  acts,  some  of  which  would  seem  too  complex  for  spi- 
nal control  without  cerebral  assistance,  as  walking,  swimming, 
playing  upon  musical  instruments,  etc.  By  referring  to  the 
diagram, '  which  is  shown  you  upon  the  blackboard,  where  a 
multipolar  spinal  cell  is  magnified,  you  will  easily  understand 
how  these  various  poles  can  be  connected  with  certain  motor, 
and  probably,  also,  with  sensory  fibers  ;  hence,  it  can  be  seen 
that  the  cell  may  receive  certain  sensory  impressions  from 
some  poles  and  send  out  certain  motor  impulses  to  the  mus- 
cles by  means  of  others,  thus  accounting  for  the  muscular 
movements  which  follow  the  irritation  of  sensory  nerves.  | 

The  sensory  fibers  enter  the  cord  at  the  posterior  roots  of 
the  spinal  nerves.  They  are  intimately  connected  with  the 
posterior  horns  of  the  gray  matter.  They  probably  ascend 
and  descend  in  the  columns  of  Burdach  for  a  certain  distance, 
and  then  decussate.  The  decussation  of  the  sensory  fibers  is 
accomplished  either  by  the  passing  of  the  fibers  themselves  to 
the  opposite  side  of  the  cord,  or  by  the  prolongation  of  some 

'  See  Figs.  117  and  118  of  this  volume. 


PATH  OF  SENSORY  IMPULSES  IN  THE  COED.  305 


Fig.  118. — MuUipolar  nerve  cell  from  the  anterior  cornu  of  the  spinal  cord  of  the  ox  ; 
magnified  200  diameters.     (Deiters.) 


306 


TEE  SPINAL    CORD. 


of  the  poles  of  the  spinal  cells  into  the  gray  matter  of  the 
opposite  side.  The  decussation  probably  takes  place  exclu- 
sively in  the  gray  matter.  While  this  decussation  seems 
positively  proven  by  all  physiological  experiment,  little  of  a 
positive  character  has,  as  yet,  been  shown  by  actual  anatomi- 
cal demonstration.  The  sensory  nerves  are  in  communication 
with  the  cortex  of  the  encephalon,  probably,  by  means  of  the 
gray  matter  of  the  spinal  cord,  which  acts  as  a  conducting 
medium  for  the  centripetal  impulses.  As  before  mentioned, 
the  gray  matter  which  surrounds  the  central  canal  of  the 
spinal  cord  seems  to  be  the  chief  channel  for  the  transmission 
of  sensory  impressions  from  the  trunk  and  the  extremities  to 
the  brain.     Thus  we  apparently  have  in  the  spinal  cord  a 


Fig.  110. 


■TranavLi'sc  section  of  tltc  (J ra}i  substance  of  the  anterior  cjrnua  of  (he  spina'  cord 
of  the  ox,  treated  loith  nitrate  of  silver.     (Grandry.) 


conducting  shaft,  to  which  the  sensory  nerves  become  joined, 
and  which  conducts  the  impressions  received  through  them  || 
to  the  ganglia  or  the  cortex  of  the  encephalon.     It  is  evi- 
dent, therefore,  that  the  sensory  nerves  are  not  continuous 


COMMISSURAL  FIBERS  OF  THE  CORD. 


307 


MS      S  M 


fibers  between  the  brain  and  the  parts  to  which  they  are  dis- 
tributed, in  which  respect  they  differ  somewhat  from  the 
motor  nerves,  whose  fibers  are  indirectly  carried  to  the  brain, 
although  the  motor  cells  of  the  cord  are 
probably  interposed. 

The  commissural  fibers  of  the  cord 
probably  exist  in  the  white  substance  of 
the  posterior  columns.'  The  spinal  cord 
may  properly  be  considered  as  a  mass  of 
superimposed  ganglia  ;  hence,  a  great  ne- 
cessity exists  for  certain  fibers  which  shall 
tend  to  unite  the  different  parts,  and  thus 
conduce  to  the  perfect  harmony  of  action 
of  the  whole.  It  is  not  possible  to  de- 
monstrate the  existence  and  exact  situa- 
tion of  such  fibers,  but  all  i)hysiological 
and  pathological  deductions  seem  to  sus- 
tain this  hypothesis.  These  fibers  have, 
probably,  a  most  important  influence 
in  the  proper  coordination  of  muscular 
movement. 

The  above  diagram  illustrates,  in  a  very  simi)le  way,  the 
general  course  of  the  motor  and  sensory  paths  of  the  spinal 
cord.  The  outer  lines  of  the  diagram  show  the  general  out- 
line of  the  spinal  cord,  which  merges  into  the  medulla  oblon- 
gata, above  ;  while  the  motor  fibers  are  designated  by  the  let- 
ter M,  and  the  sensory  fibers  by  the  letter  S,  both  where  they 
enter  the  spinal  cord  and  where  they  escape  from  it.  This 
diagram  shows  that  hotJi  the  sensory  and  motor  fibers  decus- 
sate;  but  that  the  motor  fibers  cross  in  the  medulla  oblongata 
only,  while  the  sensory  fibers  cross  soon  after  they  enter  the 
spinal  cord,  when  they  join  with  the  gray  matter,  and  use 
that  as  a  means  of  transmitting  their  sensory  impressions  to 
the  brain.  The  diagram  also  shows  that  the  sensory  fibers 
spring  from  the  posterior  roots  of  the  spinal  nerves,  since  the 

'  A.  Flint,  Jr.,  op.  cif.     The  experiments  made  to  prove  this  point  may  be  found  in 
ahnost  any  of  the  later  treatises  on  physiology. 


S' 

Fig.  120. — Course  of  motor 
and  sensory  paths  in  the 
spinal  cord.  (Brown- 
Sequard.) 

D,  decussation  of  pyramids ; 
M,  motor  paths  ;  S,  sen- 
sory paths. 


308 


THE  SPINAL    CORD. 


ganglionic  enlargement  is  depicted  uj^on  the  sensory  fibers  as 
two  small  black  dots.  Now,  it  is  easy  to  understand,  by 
means  of  this  diagram,  why  any  lesion  above  the  medulla  ob- 
longata must  produce  all  of  its  symptoms  on  the  side  of  the 
body  opposite  to  that  of  the  exciting  cause,  since  the  motor 
and  sensory  fibers  both  decussate  below  that  point ; '  w^hile  it 
also  shows  that  any  lesion  below  the  medulla  oblongata  must 
produce  motor  symptoms  upon  the  same  side  as  the  lesion, 
and,  probably,  sensory  manifestations  upon  the  side  opposite 
to  it,  since  these  latter  fibers  decussate  for  the  entire  length 


Fio.  121. — Nerve  cell  from  the  ferruginous  substance  which  forms  the  floor  of  the  rhom- 
boidal  siuus^  in  man  ;  magnified  350  diameters.     (Kolliker.) 


of  the  spinal  cord.     In  all  spinal  lesions,  causing  motor  paral 
ysis,  the  body  is  affected  below  the  point  of  disease,  since  the 
conducting  fibers  to  the  brain  are  cut  off  ;  while,  in  lesions  of 
the  posterior  portion  of  the  spinal  cord,  the  nerves  of  that 

^  This  is  not  absolutely  true,  as  all  of  the  motor  fibers  do  not  decussate  in  the 
medulla.  The  reader  is  referred  to  page  327  of  this  volume  for  the  results  of  the  investi- 
gations of  Flechsig. 


THE  SPIRAL   CORD  AS  A  NERVE   CENTER.  309 

region  may  be  rendered  incapable  of  action,  but  the  parts 
below  may  be  still  capable  of  perceiving  sensory  impressions, 
provided  that  the  gray  matter  is  left  intact,  or  sufficient  of  it 
remains  to  act  as  a  conducting  medium  to  the  brain. 

The  commissural  fibers  of  the  spinal  cord  are  not  depicted 
in  this  diagram  of  Brown- Sequard,  since  little  is  positively 
known  as  to  their  exact  situation  or  function.  As  they  are 
probably  confined  largely  to  the  posterior  half  of  the  spinal 
cord,  and  as  they  are  also  probably  intimately  associated  with 
the  coordination  of  movement,  it  is  not  difficult  to  see  why 
the  symptoms  of  ancestJiesia  and  ataxia  should  march  hand 
in  hand,  when  the  spinal  cord  is  diseased  in  this  region  ;  and 
why  neuralgic  pains  should  be  created  by  the  irritation  to 
the  sensory  nerves,  rather  than  muscular  spasm,  which  would 
only  exist  if  the  motor  nerves  were  irritated.  This  general 
subject  will,  however,  be  more  fully  discussed  in  connection 
with  the  clinical  aspects  of  locomotor  ataxia  and  degenera- 
tion of  the  posterior  portion  of  the  cord  (the  columns  of  GoU 
and  Burdach). 

Finally,  two  points  are  especially  evident  in  respect  to  the 
nerve  fibers  of  the  spinal  cord.  These  may  be  stated  as  dis- 
tinct propositions : 

1.  The  nerve  fibers  of  the  anterior  roots  have  less  numer- 
ous connections  with  the  cells  of  the  gray  substance  of  the 
cord  than  are  possessed  by  those  of  the  posterior  roots. 

2.  The  morphological  distinction  between  the  fibers  of  the 
anterior  and  posterior  roots  is,  that  the  former  are  directly 
attached  to  the  nerve  cells  by  means  of  their  nerve  prolonga- 
tions, while  the  latter  are  only  indirectly  attached  to  the  nerve 
cells,  since  they  form  nerve  plexuses  before  becoming  united 
with  the  prolongations  of  the  nerve  cells.' 

THE     SPINAL   CORD   AS    A   NERVE    CENTER. 

If  the  cord  be  separated  from  the  brain  in  a  living  animal, 
it  may  still  act  as  a  nerve  center,  independently  of  the  brain  ; 
but,  since  the  spinal  cord  is  then  in  communication  only  with 

^  A.  Flint,  Jr.,  op.  cit. 

22 


310  THE  SPINAL   CORD. 

the  nerves  which  arise  from  it,  it  can  only  affect  the  spinal 
nerves,  and  not  those  of  cranial  origin.  This  automatic  ac- 
tion of  the  spinal  cord  is  of  a  purely  reflex  type  under  such 
conditions.  It  can  be  demonstrated  by  exciting  some  one  of 
the  sensory  nerves,  when  a  muscular  response  will  be  created  ; 
hence  the  term  ''excito-motor"  is  of  ten  applied  to  this  type 
of  manifestation,  whether  occurring  during  life,  as  the  result 
of  disease  or  peripheral  irritation,  or  after  death,  as  in  the 
physiological  experiment  alluded  to.  There  are  certain  acts 
which  are  constantly  occurring  in  the  body,  such  as  the  move- 
ments of  the  pupils,  of  the  intestinal  canal,  of  respiration, 
etc.,  which  are  properly  classed  as  reflex  in  type,  but  which 
are  not  dependent  upon  the  spinal  cord  alone.  In  fact,  all 
acts  are  classed  as  belonging  to  the  reflex  type,  which  are  the 
direct  result  of  some  form  of  sensory  irritation;  but  the 
term  is  generally  used,  in  discussing  the  spinal  cord,  in  its 
most  restricted  sense,  where  the  muscular  act  is  purely  in- 
voluntary, the  result  of  some  direct  irritation  of  a  sensory 
spinal  nerve,  and  confined  to  regions  of  the  body  over  which 
the  spinal  cord  exerts  a  direct  influence.  Thus,  we  often  see 
the  muscles  of  a  paralyzed  limb  suddenly  thrown  into  in- 
voluntary and  unexpected  contraction,  when  a  draught  of 
cold  air  strikes  the  skin,  or  when  any  form  of  irritation  is  di- 
rectly applied  to  it ;  while  such  spasms  are  common  in  certain 
forms  of  spinal  disease  which  tend  to  create  irritation  of  the 
spinal  structures,  irrespective  of  any  apparent  exciting  cause. 
We  have  already  referred  to  certain  vaso-motor  centers ' 

'  The  vaso-motor  nerves  for  the  trunk,  extremities,  and  abdominal  viscera  probably 
originate  in  the  following  manner  (see  researches  of  Vulpian,  Schiff,  Cyon,  Claude  Ber- 
nard, and  the  later  researches  of  Dastrc,  Tiaffont,  and  Morat)  : 

Those  for  the  upper  extremities  are  derived — 

1.  From  the  inferior  cervical  and  superior  thoracic  ganglion,  uniting  at  the  brachial 
plexus,  close  to  the  first  .rib  ; 

2.  From  the  nerve  roots  of  the  brachial  plexus  ; 

3.  From  the  thoracic  cord  of  the  sympathetic,  and  from  the  nerve  roots  of  the  third, 
fourth,  fifth,  sixth,  and  seventh  dorsal  nerves,  principally  from  the  third  and  seventh. 

Those  for  the  lower  extremities  proceed — 

1.  From  the  spinal  cord  with  the  sciatic  and  crural  nerves : 

2.  From  the  abdominal  cord  of  the  sympathetic. 

The  abdominal  viscera  are  supplied  with  fibers  arising  from  a  considerable  length  of 


CELIO-SPINAL  AND   GENITO-URINARY  CENTERS.        311 

which  exist  in  the  substance  of  the  spinal  cord,  the  two  most 
important  of  w^hich  are  the  cilio- spinal  center  and  the  center 
for  the  genito-urinary  apparatus.  The  former  of  these  is 
situated  in  the  cervical  region,  and  exerts  some  marked  eifects 
upon  the  eye,  face,  and  neck ;  while  the  latter  is  situated  in 
the  dorso-lumbar  region  of  the  cord.  If  the  medulla  oblon- 
gata be  considered  as  the  upper  expansion  of  the  spinal  cord 
(and  there  are  many  anatomical  reasons  for  thus  considering 
it),  all  the  centers  mentioned  as  situated  in  that  ganglion  may 
be  included  among  the  spinal  centers  of  automatic  action. 
Some  authors  have  gone  so  far  as  to  locate  in  the  spinal  cord 
certain  centers  which  preside  over  the  acts  of  micturition,  de- 
fecation, parturition,  erection,  etc.,  and  experiment  seems  to 
give  reason  to  hope  that  a  more  definite  ground  will  be  af- 
forded for  such  belief,  although  little  of  a  positive  character 
can  as  yet  be  given  in  regard  to  their  situation. 

It  has  also  been  claimed  that  the  spinal  nerves  exercise  a 
tonic  action  over  the  muscles  which  move  the  different  por- 
tions of  the  skeleton,  in  the  same  way  as  the  vaso-motor 
nerves  exercise  such  a  power  over  the  muscular  libers  in  the 
coats  of  the  blood-vessels ;  and  certain  experimental  pheno- 
mena, chiefly  the  gaping  of  a  wound  in  muscular  tissue,  have 
been  advanced  to  sustain  this  theory.  It  is  not,  however, 
fully  sustained  by  all  the  facts,  '  and  is  not  generally  ac- 
cepted by  the  leading  physiologists. 

We  have  come  to  learn  that  each  group  of  cells — perhaps 
each  cell — in  this  gray  matter  represents  a  certain  kind  of 
intelligence ; '  and  that  these  cells  are  probably  in  communi- 
cation with  one  another  by  means  of  white  fibers.  It  is  the 
sum  total  of  these  intelligences  that  imparts  to  the  cord  its 
characteristics  as  an  organ.     As  each  one  of  these  cellular 

the  dorsal  and  lumbar  cord,  and  running  within  the  sheath  of  the  splanchnic  nerve,  as 
well  as  by  fibers  from  the  abdominal  cord  of  the  sympathetic. 

The  vaso-motor  nerves  of  the  head  and  face  talcs  their  origin  from  what  is  known  as 
the  "  cilio-spinal  center,"  and  when  this  center  is  destroyed  there  ensues  a  marked 
dilatation  of  the  capillaries  of  the  head  and  face. 

^  For  the  discussion  as  to  the  merits  and  demerits  of  this  theory,  the  reader  is  re 
ferred  to  the  late  text-book  of  Michael  Foster  on  physiology. 

2  L.  C.  Gray,  "Annals  of  Anatomical  and  Surgical  Society,"  October,  1880. 


312  THE  SPINAL   CORD. 

groups  and  its  inherent  intelligence  is  more  or  less  independ- 
ent of  all  others,  so  the  combined  intelligence  of  the  cord's 
gray  matter  is  independent  of  the  combined  intelligence  of 
other  collections  of  gray  matter ;  and  it  is  a  recognized  fact 
that  the  spinal  cord  has  a  "function"  of  its  own.  This  has 
been  exemplified  by  experiments  upon  headless  frogs  and  de- 
capitated human  beings.  Cut  off  the  head  of  a  frog,  peimit 
it  to  recover  from  the  shock  of  the  operation,  then  pinch  its 
skin,  and  it  will  hop  away ;  or,  throw  it  into  water,  and  it 
will  swim.  Place  a  drop  of  acetic  acid  upon  the  belly  of  such 
a  frog,  and  it  will  endeavor  to  brush  away  the  irritation  with 
one  foot.  Now  amputate  the  leg  of  this  foot  at  the  knee. 
The  animal  will  make  several  futile  attempts  to  reach  the 
irritated  spot  with  the  stump,  and,  failing,  will,  after  some 
hesitation,  make  use  of  the  uninjured  limb  for  this  purpose. 
It  is  easy  to  repeat  this  well-known  experiment  of  Pfliiger's.' 
Robin  *  witnessed  some  most  instructive  phenomena  in  a  crimi- 
nal whose  head  had  been  removed  an  hour  previous  at  the 
level  of  the  fourth  cervical  vertebrae.  The  skin  around  the 
nipple  was  scratched  with  the  point  of  a  scalpel.  Immedi- 
ately there  ensued  a  series  of  rapid  movements  in  the  upper 
extremity,  which  had  been  extended  upon  the  table.  The 
hand  was  brought  across  the  chest  to  the  pit  of  the  stomach, 
simultaneously  with  a  semi-flexion  of  the  forearm  and  inward 
rotation  of  the  arm — a  movement  of  defense,  as  it  were.  All 
this  teaches  us  the  more  clearly  to  understand  that  it  is  the 
intelligence  of  the  cord's  gray  matter  that  is  called  into  play 
in  a  thousand  actions  that  must  take  place  without  the  aid  of 
that  conscious  intelligence  which  we  call  "mind."  The  intel- 
ligence of  the  spinal  cells  is  quite  sufficient  to  enable  men  to 
walk,  to  play  on  musical  instruments,  to  become  experts  in 
handiwork,  to  ride  on  horseback,  whether  awake  or  asleep,  to 
become  acrobats,  and  to  unconsciously  acquire  such  a  hand- 
writing that  its  minute  peculiarities  shall  be  unerringly  recog- 
nized by  the  trained  eye. 

*  Pfliiger,  "Die  sensorische  Function  des  Riickenmaiks,"  1853. 
«  "Jour,  de  TAnat.  et  de  la  Physiol.,"  Paris,  1860. 


KINESOniC  AND  JESTHESODIG  SYSTEMS.     *         313 
CLIKICAL   POINTS   PERTAININ^G   TO   THE   SPINAL   CORD. 

From  the  physiological  experiments  as  to  the  functions  of 
the  different  columns  of  the  cord,  it  now  seems  possible  to 
divide  the  spinal  cord  into  two  great  subdivisions,  which  will 
be  of  interest  from  a  purely  clinical  standpoint,  as  well  as 
from  a  physiological  aspect.  The  first  of  these  includes  the 
entire  antero-lateral  columns,  and  the  anterior  horns  of  the 
gray  matter,  and  is  the  probable  path  of  all  motor  impulses 
which  traverse  the  cord,  as  well  as  the  seat  of  "trophic 
influences "  upon  tissues.  The  latter  includes  the  posterior 
columns  and  the  posterior  horns  of  the  gray  matter,  and  is 
the  probable  path  of  all  the  sensory  impulses,  while  it  also  is 
associated  with  the  function  of  coordination  of  movement. 
Now,  both  of  these  subdivisions  include  several  parts  of  the 
spinal  cord,  which  have  been  separately  named  in  previous 
pages;  hence,  the  term  '^  system"  is  applied  to  both,  the 
former  being  named  the  ''  Mnesodic  system,'^''  and  the  latter 
the  '' cBstliesodic  system^  These  names  will  be  constantly 
used,  therefore,  when  the  portions  of  the  cord  which  con- 
vey either  motor  or  sensory  impulses  are  spoken  of  as  a 
whole  ;  while  the  other  names  applied  to  special  portions 
of  the  cord  will  chiefly  be  used  in  defining  the  situations 
of  special  lesions  whose  symptomatology  may  be  under  dis- 
cussion. 

If  we  are  to  attempt  to  grasp  the  symptoms  by  which  the 
various  lesions  of  the  spinal  cord  may  be  recognized  during 
life,  and  to  understand  why  certain  effects  must  be  produced 
(when  the  situation  of  the  lesion  is  known  to  us),  we  must 
make  some  classification  of  the  diseases  which  affect  the  spinal 
cord  on  such  an  anatomical  and  physiological  basis  as  shall 
naturally  tend  toward  the  constant  application  of  these 
branches  of  medical  science  to  the  symptoms  presented  by 
the  patient.  It  has  been  customary  with  most  of  the  late 
authors  upon  the  special  subject  of  nervous  affections  to  con- 
sider the  diseases  of  the  motor  regions  and  of  the  sensory 
regions  of  the  cord  separately;  using  the  term  ''systematic 


314  THE  SPINAL   CORD. 

lesions''^  to  express  the  fact  that  all  of  those  diseases, which 
are  not  purely  local,  affect  either  the  kinesodic  or  sesthesodic 
systems.  When  we  speak  of  systematic  lesions,  therefore, 
we  mean  those  types  of  disease  which  tend  to  diffuse  them- 
selves, for  a  greater  or  less  extent,  upward  and  downward, 
without  extension  to  the  adjacent  columns  ;  thus  the  columns 
of  GoU  and  of  Burdach  may  be  involved  in  the  sesthesodic 
system,  the  lateral  columns  and  the  columns  of  Tiirck  may 
be  involved  in  the  kinesodic  system,  while  the  anterior  or 
posterior  horns  or  central  part  of  the  gray  matter  may  be 
the  seat  of  disease,  irrespective  of  the  other  parts  of  the 
cord. 

In  contradistinction  to  the  systematic  lesions,  certain 
types  of  disease  tend  to  spread  laterally,  and  thus  to  involve 
different  columns  of  the  cord  in  succession.  These  are  grouped 
under  the  general  head  of  "focal  lesions  "  or  '' non- systematic 
lesions,^''  In  this  form  of  degeneration,  or  of  new  tissue 
development,  the  extension  is  usually  limited  in  a  vertical 
direction,  but  *it  may  extend,  laterally,  not  only  to  diverse 
columns,  but  may  even  involve  both  the  kinesodic  and 
sesthesodic  systems  in  its  progress. 

It  will  exceed  the  proper  scope  of  the  course  of  lectures 
which  I  have  prepared  for  this  winter,  to  enter  into  a  full  de- 
scription of  the  symptoms  of  all  of  the  diseases  of  the  spinal 
cord ;  but  it  is  important  that  you  start  with  a  genei^al  classi- 
fication of  the  diseases  which  may  affect  this  region,  in  order 
that  you  may  properly  understand  the  meaning  of  terms 
which  you  will  find  growing  into  use  with  astonishing  rapid- 
ity. It  is  also  to  be  remembered  that  the  classification  which 
I  have  given  you  is  based  on  anatomy  and  pathology,  and 
may  differ  markedly  from  those  of  some  authors  with  which 
you  may  be  familiar ;  a  little  study  will,  however,  remove  all 
confusion,  and  perhaps  add  to  your  more  perfect  comprehen- 
sion of  the  subject. 


SYSTEMATIC  LESIONS  OF  JESTHESODIG  SYSTEM.       315 


A   CLASSIFICATION   OF   THE   DISEASES   OF   THE   SUBSTANCE   OF   THE 
SPINAL   CORD.       (after   SEGUIN.) 

r  Sclerosis  of  the  columns  of  GoU, 
Lesions  of  the  ^s-  J   Sclerosis  of  the  columns  of  Burdaoh  (locomo- 
thesodic  System,      j  tor  ataxia), 

(^  Ascending  degeneration, 
f  Sclerosis  of  the  anterior  columns, 
SYSTEMATIC  "   |  Sclerosis  of  the  lateral  columns  (tetanoid  para- 

LESIONS.         ^  plegia), 

Degeneration  of  the  postero-lateral  columns, 
■<    Myelitis  of  the  anterior  horns  (atrophic  spinal 
paralysis). 
Degeneration  of  the  ganglion  cells  of  the  ante- 
rior horns  (progressive  muscular  atrophy), 
Central  myelitis. 
Traumatism  of  the  cord, 


Lesions  of  the  Ki- 
nesodic  System. 


"  NON-SYSTEM- 
ATIC" OR  "FO- 
CAL" LESIONS. 


Compression  of  the  cord,  by 


\  Bone  or 


I  Tumors, 
-{  Transverse  sclerosis  of  the  cord. 
Transverse  softening  of  the  cord, 
I   Haemorrhage  into  the  cord, 
(^  Tumors  of  the  cord. 


"SYSTEMATIC  LESIONS'^   OF  THE   "  ^STHESODIC   SYSTEM." 

In  the  table '  which  I  have  written  out  for  your  inspection, 
you  will  perceive  that  the  systematic  lesions  may  affect  either 
the  sesthesodic  or  kinesodic  systems  of  the  spinal  cord,  while 
the  focal  lesions  are  not  thus  separated,  since  they  tend  to 
extend  in  a  transverse  direction,  and  thus  may  be  found  in 
both.  As  the  sesthesodic  system  presents  only  two  well-recog- 
nized and  understood  conditions,  we  will  first  study  the  gen- 
eral effects  of  extending  disease  which  is  confined  either  to 
the  columns  of  Goll  or  of  Burdach. 

We  might  begin,  possibly  with  advantage,  by  stating  that 
the  general  results  of  any  lesion  situated  back  of  the  posterior 
gray  horn  of  the  cord  must  manifest  itself,  if  our  previous  de- 
ductions are  correct,  by  symptoms  referable  only  to  sensation 
and  coordination.  This  we  find  to  be  approximately  correct. 
We  have  in  this  type  of  cases  ancesthesia^  Jiypercesthesia^  or 
numbness.,  and  also  pain  (usually  possessing  some  special 
characteristics  which  are  of  clinical  value) ;  while  coordi- 
nation is  unquestionably  affected  as  well,   since  a  peculiar 


See  page  315  of  this  volume. 


316  THE  SPINAL   CORD. 

disorder  of  voluntary  movements,  which  constitutes  true 
"ataxia,"  is  usually  developed.  Our  previous  statements  as 
to  the  path  of  the  motor  impulses  of  the  cord  seem  to  be  con- 
firmed by  the  absence  of  either  spasm  or  true  paralysis  of 
the  muscles  below  the  lesion. 

The  question  now  arises,  "  Can  we  tell  whether  the  disease 
is  confined  to  the  columns  of  Goll  or  of  Burdach  ? "  We  can 
undoubtedly  locate  the  lesion  in  the  opposite  side  of  the  cord 
from  that  of  the  body  upon  which  certain  symptoms  are  well 
marked ;  but  can  we  tell  positively  whether  the  lesion  is  pro- 
gressing in  the  inner  or  outer  column  of  the  posterior  half  of 
either  side  of  the  cord  which  shows  the  evidence  of  disease  I 

SCLEROSIS   OF  THE   COLUMJ^S  OF   GOLL. 

As  regards  the  columns  of  Goll,  I  feel  myself  forced  to  say 
that  I  do  not  believe  that  localized  disease  can  be  positively 
diagnosed  when  confined  to  these  columns;  although,  from 
certain  pathological  deductions,  we  can  often  infer  that  it 
exists^  since  it  has  been  found  to  occur  as  a  secondary  result 
of  those  other  lesions  which  are  capable  of  producing  an  as- 
cending or  descending  degenerative  process  in  the  spinal  cord. 
As  the  columns  of  Goll  are  large  and  distinct  in  the  cervical 
region  of  the  cord,  but  become  narrower  and  narrower  as  the 
lower  portion  of  the  cord  is  reached,  the  lesion  of  this  column 
becomes  more  evident  to  ocular  demonstration,  when  present, 
as  you  ascend  the  cord.  The  entire  length  of  either  column 
may  be  affected,  or  only  portions  of  it.  In  the  ascending 
form  of  secondary  degeneration  of  these  columns,  the  lesion 
is  always  observed  above  the  seat  of  the  exciting  cause.  This 
lesion  has  never  been  traced,  so  far  as  my  researches  go,  above 
the ''calamus  scriptorius." 

SCLEROSIS   OP  THE   COLUMNS   OF   BURDACH    (LOCOMOTOR   ATAXIA). 

The  columns  of  Burdach  are  the  seat  of  sclerosis  more 
commonly  than  those  of  Goll,  since  this  type  of  change  pro- 
gresses, as  a  rule,  from  the  posterior  root  zones  inward,  and 
thus  only  affects  the  columns  of  Goll  after  those  of  Burdach 


PROGEESSIVE  LOCOMOTOR  ATAXIA,  3I7 

have  become  seriously  impaired.  In  all  those  cases  where  the 
symptoms  of  pain  and  alteration  in  the  sensibility  of  parts 
precede  those  of  ataxia,  we  find  the  columns  of  Burdach  first 
affected  with  a  systematic  lesion,  and,  afterward,  those  of 
GqII.  The  investigations  of  Pierret  and  Charcot  seem  to  de- 
monstrate that  the  condition  of  sclerosis  of  the  columns  of  Bur- 
dach usually  begins  in  the  lumbar  enlargement,  and  tends  to 
creep  gradually  upward  toward  the  medulla  oblongata,  so  that 
the  entire  length  of  the  cord  may  become  hardened  and  atro- 
phied ;  while  the  same  condition  of  the  columns  of  Goll  is 
usually  found  to  coexist,  but  may  be  looked  upon  as  a  sec- 
ondary result  of  the  former. 

Now,  we  have  mentioned  certain  peculiar  symptoms  which 
point,  when  present,  to  some  disease  of  the  posterior  columns 
of  the  spinal  cord,  among  which  come  pain,  liyjpercBstliesia^ 
numbness^  ancEsfhesia^  and  symptoms  of  incoordination 
(ataxia)  when  the  disease  is  far  advanced.  We  discover  no 
motor  symptoms,  as  the  muscular  power  appears  to  be  normal 
in  all  respects,  except  in  coordinate  movement ;  and  no  ''tro- 
phic changes  "  in  tissues  are  produced,  as  would  ensue  if  the 
anterior  portion  of  the  cord  were  involved.  It  will  help  us  to 
recognize  this  disease,  if  we  will  study  a  little  more  in  detail 
each  of  these  various  manifestations  of  posterior  spinal  lesions. 

In  the  first  place,  the  pains  of  this  type  of  sclerosis  are 
peculiar.  They  do  not  follow  the  course  of  special  nerve 
trunks,  as  do  neuralgic  pains,  but  are  more  localized.  They 
are  vagrant  in  character,  since  they  affect  innumerable  spots 
in  the  region  which  is  presided  over  by  the  nerves  connected 
with  the  diseased  portion  of  the  cord  ;  and  so  marked  is  this 
peculiarity  that  a  patient  who  has  long  suffered  with  these 
pains  can  not  well  select  any  spot  which  has  entirely  escaped 
them.  Again,  the  pains  vary  in  their  intensity,  since  they  are 
more  or  less  paroxysmal,  and  often  show  exacerbations  due  to 
atmospheric  changes.'  These  exacerbations  may  occur  every 
few  minutes  for  some  hours,  and  may  then  disappear  for 

'  Dampness  seems  to  increase  the  severity  of  these  pains,  thus  oftqn  tending  to  mis- 
lead the  practitioner  as  to  their  rheumatic  origin. 


318  THE  SPINAL   CORD. 

days  or  weeks  ;  the  area  covered  by  them  may  vary  from  that 
of  a  small  point  to  that  of  your  hand  ;  and  they  may  be  re- 
ferred to  the  skin  alone,  the  muscles,  the  joints,  the  bones, 
or,  in  rare  cases,  to  the  viscera.  These  pains  are  usually  of  a 
sudden  character,  and  extremely  severe.  They  assume  the 
character  of  stabbing,  tearing,  or  shooting  sensations,  which 
often  cause  the  patient  to  shriek  in  agony ;  while  the  skin 
over  the  circumscribed  spot  is  rendered  hypersesthesic  to 
slight  pressure,  although  firm  pressure  often  affords  relief. 
The  terms  '^fulgurating"  and  "  terebrating  "  are  of  ten  applied 
to  these  pains,  from  their  sudden  onset  and  their  similarity  to 
the  effects  of  a  passage  of  a  strong  electric  current.  In  fact, 
the  distinctive  characteristics  of  the  pain  of  sclerosis  of  the 
posterior  columns  of  the  spinal  cord  are  so  well  defined  that  I 
seldom  hesitate  to  predict  the  development  of  later  ataxic 
symptoms  from  this  guide  alone.  It  is  usually  confined  to  the 
lower  extremities  (toes,  foot,  shin,  calf,  and  thigh),  but  it 
sometimes  affects  the  trunk  and  the  upper  extremity,  and,  in 
very  rare  cases,  the  head.  It  is  to  be  differentiated  from  the 
pain  of  rheumatism  or  of  a  simple  neuralgia,  and,  as  it  is  the 
initial  symptom  of  a  serious  and  incurable  disease,  it  should 
be  recognized  early. 

Touching  upon  this  point.  Professor  E.  C.  Seguin,  in  a  late 
lecture,  puts  the  diagnosis  of  this  affection,  with  his  accus- 
tomed clearness,  as  follows : 

"  The  only  two  conditions  in  which  pains  somewhat  resem- 
bling fulgurating  pains  occur,  in  my  experience,  are  paralytic 
dementia  and  gout.     In  the  former  disease,  slight  fulgurating 
pains — 'smaller'  pains,  if  I  may  be  allowed  the  expression — ^ 
are  described  by  the  patients ;  but,  in  many  of  these  cases 
autopsy  shows  that,  besides  the  cerebral  lesions  proper  to  the^ 
disease,  the  posterior  columns  of  the  cord  exhibit  pathological 
alterations ;  so  that  these  cases  are,  after  all,  quasi-tdiheiiG. 
The  sharp  pains  of  gout  are  short,  stabbing  pains  in  the  skii 
of  various  parts  of  the  body,  compared  by  the  patients  t( 
the  prick  of  a  needle,  cold  or  hot.     There  is  no  tendency  t( 
repetition  of  the  pain  in  one  spot  for  hours  or  days ;  the  sen- 


TEE  PAINS  OF  LOCOMOTOR  ATAXIA.  319 

sations  appear  in  various  parts  of  the  body,  and  are  bear- 
able. 

'*  The  differential  diagnosis  of  fulgurating  pains  from  the 
pains  of  neuralgia,  strictly  speaking,  is  very  easy.  In  neural- 
gia the  pain  is  in  the  course  and  distribution  of  one  or  two 
(single)  nerve  trunks  and  their  branches ;  it  may  be  parox- 
}'smal,  but  does  not  assume  the  excessive  irregularity  of  ta- 
])etic  pains,  viz.,  agony  for  a  few  hours,  and  freedom  from 
pains  for  hours,  days,  or  weeks.  The  hypersesthesia,  in  ful- 
gurating pains,  is  at  the  seat  of  pain.  In  neuralgia,  we  find 
regular  '  tender  points '  along  the  nerve  trunk,  or  where  its 
l)ranches  become  superficial.  The  lightest  touch  causes  pain 
in  the  painful  districts  in  tabes,  while  the  tenderness  of 
nerves  in  neuralgia  is  usually  demonstrable  only  by  firm, 
localized  pressure.  Further,  true  neuralgia  is' seldom  bilat- 
eral, while  it  is  the  rule  for  fulgurating  pains  to  appear  on 
both  sides  of  the  median  line — in  both  lower  extremities,  for 
example.  A  last  important  distinction  is  that  neuralgia  is 
relievable  or  curable,  whereas  fulgurating  pains  are  practi- 
cally incurable,  and  fully  relieved  only  by  morphia  injections. 

''The  confusion  so  often  made  between  'rheumatism'  and 
the  first  stage  of  sclerosis  is  even  less  pardonable.  Of  course, 
no  practitioner  would  mistake  fulgurating  pains  for  articular 
iheumatism ;  the  error  is  with  respect  to  'rheumatism,'  so 
called,  affecting  muscular  masses  and  aponeuroses.  In  these 
affections  the  pains  are  usually  dull,  nearly  constant,  and  dis- 
tinctly aggravated  by  movements.  Pressure  must  be  firmly 
made  upon  the  parts  to  produce  pain,  whereas  in  fulgurating 
pains  the  condition  is  one  of  cutaneous  hyperalgesia  under  a 
slight  touch.  Again,  this  '  rheumatic '  condition  is  distinctly 
amenable  to  treatment  (counter-irritants,  etc.),  whereas  the 
pains  of  posterior  spinal  sclerosis  are,  in  one  sense,  incurable." 

Now,  this  symptom  may  exist  for  years  without  the  de- 
velopment of  marked  anaesthesia  or  of  ataxia,  and  often  both 
the  patient  and  the  physician  are  inclined  to  speak  of  these 
pains  as  dependent  upon  some  rheumatic  diathesis,  rather 
than  as  a  precursor  of  an  incurable  affection.     The  peculiar 


320  THE  SPINAL   CORD. 

hypersesthesia  which  exists  in  the  patches  of  skin  affected 
with  the  pain,  both  during  the  paroxysm  and  sometimes  for 
hours  afterward,  affords  a  point  of  great  diagnostic  value. 

As  regards  the  second  diagnostic  symptom — ancBsthesia — 
it  is  claimed  that  an  alteration  in  the  sensibility  of  the  af- 
fected parts  can  be  detected  in  the  earliest  stages  of  the  dis- 
ease, as  well  as  later  on  ;  but,  in  the  former  case,  the  loss  of 
sensation  is  localized  in  distinct  spots  or  patches  of  integu- 
ment (usually  upon  the  lower  extremities,  but,  possibly,  upon 
the  trunk  and  arms,  if  the  disease  be  extensive),  while,  in  the 
later  stages,  the  soles  of  the  feet  become  deprived  of  sensi- 
bility, and  the  'ansesthetic  condition  tends  to  extend  upward 
along  the  legs  and  thighs  until  the  whole  of  the  affected  re- 
gions may  be  dead  to  all  sensations.  Now,  it  is  this  very  con- 
dition of  the  integument  that  probably  causes  the  symptom 
which  is  regarded  by  many  physicians  as  pathognomonic  of 
locomotor  ataxia — staggering  or  falling,  when  the  eyes  are 
closed  and  the  patient  attempts  to  stand  erect — and  no  test  is 
more  worthless  of  this  special  affection.  I  have  seen  a  patient 
made  to  fall,  when  his  eyes  were  closed,  by  simply  freezing 
the  soles  of  the  feet  so  as  to  render  them  incapable  of  sensa- 
tion, while  it  is  well  recognized  that  the  same  symptom  is  met 
with  in  the  anaesthesia  which  follows  or  accompanies  hysteria, 
myelitis  of  the  posterior  horns,  etc.  That  patients  afflicted 
with  locomotor  ataxia  do  stagger  and  often  fall,  when  obliged 
to  stand  erect  with  closed  eyes,  no  one  can  deny,  but  that  it 
has  no  special  diagnostic  value  can  now  be  as  positively  stated. 

In  the  final  stages  of  sclerosis  of  the  posterior  columns, 
symptoms  of  ataxia  develop.  The  walk  of  the  patient  now 
becomes  of  a  peculiar  character.  The  legs  are  jerked  about 
in  an  aimless  manner,  and  the  feet  are  brought  down  in  a 
stamping  way  which  is  totally  different  from  the  gait  of  pa- 
i-alysis.*    The  separate  muscles,  when  tested,  show  an  unim- 

'  This  symptom  may  develop  at  a  variable  period  from  the  commencement  of  the 
neuralgic  pains  (the  duration  of  the  pains  varying  from  three  months  to  ten  or  more 
years).  The  heel  strikes  the  ground  forcibly  in  walking.  If  the  upper  extremities  are 
involved,  the  fingers  and  arms  perform  unnecessary  movements  to  reach  a  given  point, 
and  oscillate  when  a  given  action  is  attempted. 


VARIETIES  OF  ATAXIC  MANIFESTATIONS.  321 

paired  power,  but  the  large  groups  of  muscles  can  not  be 
employed  in  rhythmical  succession.  The  patient  begins  to 
notice,  in  the  early  symptoms  of  this  condition,  a  sense  of 
distrust  in  himself  in  crossing  a  street  or  in  performing  any 
act  which  calls  for  sudden  and  positive  muscular  coordina- 
tion. Later  on,  walking  becomes  almost  impossible  if  the 
ataxic  symptoms  develop  rapidly,  and  the  patient  is  liable  to 
fall,  in  his  efforts  to  avoid  any  special  danger,  as  in  traveling 
the  streets. 

One  of  the  earliest  evidences  of  incoordination  of  movement 
usually  perceived  by  tabetic  patients  is  a  difficulty  in  direct- 
ing their  feet  toward  any  object  of  small  size,  such  as  a  car- 
riage-step, stirrup,  etc.  A  difficulty  is  also  experienced  by 
many  in  ascending  long  flights  of  stairs,  as  the  equilibrium  is 
preserved  with  some  difficulty,  on  account  of  an  uncertainty 
in  placing  the  feet  upon  the  stairs.  Later  on  in  the  disease, 
the  feet  are  swung  in  a  circle,  in  contrast  to  the  straight  pro- 
gression of  the  normal  step,  since  the  equilibrium  is  thus 
more  easily  preserved.  This  has  been  compared  to  the  swing- 
ing motion  of  the  tight-rope  performer.  The  sole  of  the  foot 
is  generally  brought  down  after  the  heel  strikes  the  ground, 
thus  often  giving  a  flapping  sound  to  the  step.  The  jerking 
gait  of  well-marked  ataxia  could  never  be  mistaken  for  that 
of  paralysis. 

When  the  upper  extremities  are  affected,  the  motions  of 
the  hand  show  even  more  decided  evidences  of  incoordination. 
Such  patients,  when  asked  to  place  the  tip  of  their  finger 
upon  any  designated  spot  on  the  face  (provided  the  eyes  are 
first  closed,  in  order  to  prevent  the  use  of  vision  as  an  aid  to 
movement),  utterly  fail  to  perform  the  act,  often  touching  a 
spot  one  or  two  inches  from  that  upon  which  they  intended 
to  place  their  finger.  With  the  eyes  open,  a  glass  of  water  is 
carried  to  the  mouth  with  a  trembling  of  the  hand  and  partial 
spilling  of  its  contents  ;  and  the  finger  is  placed  upon  any 
point  designated  upon  the  face  by  being  suddenly  darted 
forward,  rather  than  by  a  deliberate  movement.  The  hand- 
viTiting  is  markedly  altered,    especially  in  respect  to    the 


322  THE  SPINAL   CORD. 

rounded  letters,  such  as  d^  ft,  o,  <?,  z ;  and  this  is  even  more 
marked  when  writing  is  attempted  with  the  eyes  closed,  as  it 
is  then  almost  unintelligible. 

The  complex  movements  of  the  lingers,  required  for  the 
act  of  buttoning  or  unbuttoning  the  clothing,  and  in  picking 
up  a  pin  from  the  floor,  are  performed  with  so  much  difficulty 
that  they  afford  two  admirable  tests  for  this  disease,  provided 
the  upper  extremity  be  involved. 

Tabetic  patients  usually  walk  with  their  eyes  fixed  upon 
the  feet,  as  vision  aids  them  materially  in  guiding  their 
movements  of  progression ;  hence,  we  invariably  find  that 
closing  the  eyes  causes  a  marked  alteration  in  the  ataxic 
manifestations,  oftentimes  causing  them  to  fall  when  required 
to  stand  motionless. 

It  must  be  remembered,  however,  as  was  brought  out  in 
the  lectures  upon  the  brain,'  that  certain  forms  of  intra-cra- 
nial  diseases  tend  to  produce  the  same  symptoms,  so  that 
ataxic  movements  are  only  confirmatory  of  a  sfjinal  disease 
which  has  previously  manifested  itself  by  well-marked  sen- 
sory symptoms. 

There  are  two  other  symptoms  referable  to  the  sensory 
nerves  which  are  of  value  in  deciding  as  to  the  probable  ex- 
istence of  posterior  spinal  sclerosis,  viz.,  a  retardation  of  sen- 
sation and  diminished  reflex  movement. 

If  we  prick  the  skin  of  a  patient  suffering  from  this  type 
of  disease,  and  count  the  time  which  intervenes  between  the 
time  of  the  puncture  and  the  time  when  the  patient  perceives 
it  (provided  the  eyes  be  closed,  so  as  to  prevent  any  visual 
recognition  of  the  pricking  of  the  part),  we  will  often  find 
that  an  interval,  varying  from  ten  to  one  hundred  or  more 
seconds,  may  be  detected.  This  has  been  explained,  by  sup- 
posing that  the  sclerosis  has  created  such  pressure  upon  the 
sensory  nerve  filaments  as  to  partially  or  nearly  completely 
destroy  the  axis  cylinders.  This  symptom  is  invariably  fol- 
lowed sooner  or  later  by  complete  anaesthesia,  and  by  a 
sense  of  numbness   which  extends   upward  from   the  feet, 

^  Sec  pages  64  and  66. 


REFLEX  TESTS  FOR  LOCOMOTOR  ATAXIA.  323 

since  it  is  usually  perceived  in  the  lower  extremity  rather 
than  in  the  upper. 

In  addition  to  the  sensory  manifestations  already  dis- 
cussed, this  disease  tends  to  extend  upward  along  the  cord 
until  the  optic  apparatus  becomes,  in  some  way,  markedly 
affected.  The  perception  of  color  is  often  rendered  obscure, 
or  entirely  lost  for  the  red  and  green  tints  ;  while  the  patient 
may  possess  a  normally  acute  perception  of  the  yellow  or 
blue  tints,  or  even  have  an  unnatural  acuteness  in  detecting 
delicate  shades  of  these  colors. 

In  some  instances,  ptosis,  diplopia,  and  a  marked  altera- 
tion in  the  reflex  movement  of  the  iris  to  varying  degrees  of 
light,  are  developed  ;  and  these  may  prove  of  great  advantage 
to  you  in  tending  to  confirm  the  possible  existence  of  this 
type  of  spinal  sclerosis. 

During  the  first  stage  of  the  disease,  when  the  fulgurating 
pains  are  present,  all  the  reflex  movements  which  seem  to  be 
controlled  either  entirely  or  in  part  by  the  spinal  cord  are  di- 
minished. As  examples  of  this  fact,  we  frequently  see  that 
the  pupils  are  either  smaller  than  normal,  or  irregular  as  re- 
gards their  size,  or  that  they  do  not  proi^erly  respond  to  fine 
variations  in  the  intensity  of  light,'  and  that  the  muscles  do 
not  respond  to  sensory  stimulation  of  the  skin.  If  the  knee 
be  semi-flexed  during  the  stage  of  fulgurating  pains,  or  even 
when  the  ataxic  symptoms  have  been  developed,  and  the  liga 
mentum  patellae  be  struck  sharply  with  the  flnger-end,  you 
will  notice  that  the  muscles  of  the  quadriceps  extensor  of  the 
thigh  fail  to  produce  any  responsive  movement  of  the  limb, 
since  the  reflex  action  of  the  spinal  cord  is  impaired.  This 
test  is  one  which  is  now  regarded  by  specialists  in  nervous 
diseases  as  one  of  great  value,  in  deciding  as  to  the  presence 
of  posterior  spinal  sclerosis,  and  it  is  known  as  the  '' patella 
reflex"  test.' 

'  See  page  148  of  this  volume. 

2  In  reference  to  the  diminution  of  the  different  reflexes,  much  has  ah-cady  been  men- 
tioned in  preceding  pages.  I  quote,  however,  a  summary  of  Professor  Seguin  upon  this 
point,  as  a  general  resume. 

"  We  test  the  so-called  patellar  reflex,  or  knee  reflex,  or  patellar  tendon  reflex,  in  the 


324  THE  SPINAL   CORD. 

Now,  it  must  be  evident  to  you  all,  that  the  symptoms 
which  have  been  hastily  enumerated  as  indicating  a  lesion  in 

following  ways :  the  patient,  being  seated,  is  told  to  cross  one  leg  over  the  other  in  a 
natural  manner,  and  to  let  the  muscles  relax ;  or,  seated,  we  place  our  left  hand  under  the 
popliteal  space,  tell  the  patient  not  to  help  us,  to  let  the  leg  hang  loose,  or,  in  popular 
parlance,  '  dead,'  and  lift  the  whole  limlf  so  that  the  foot  swings  a  couple  of  inches 
above  the  floor ;  then  we  tap  the  skin  over  the  whole  of  the  region  from  the  insertion  of 
the  quadriceps  femoris  to  the  tuberosity  of  the  tibia,  with  one  or  two  finger  tips  applied 
as  in  percussion.  The  place  whence  a  reflex  quadriceps  contraction  is  most  apt  to  occur 
is  about  midway  between  the  lower  end  of  the  patella  and  the  tibial  protuberance.  The 
taps  should  be  gentle  at  first,  and,  if  these  fail,  harder  ones  are  to  be  tried.  A  third 
mode  of  procedure,  which  is  very  good  indeed,  is  to  seat  the  patient  on  a  table  so  that  his 
legs  dangle  some  two  or  three  inches  beyond  its  edge ;  then  we  tap  the  patellar  region  as 
above  described,  without  supporting  the  thigh  with  our  left  hand.  The  test  may  be  well 
done  through  the  patient's  clothing,  yet  it  is  desirable,  especially  in  doubtful  cases,  to  tap 
the  bare  skin.  Another  important  precaution  is  to  secure  the  absolute  relaxation  of  the 
patient's  muscles,  and  to  divert  his  attention  from  what  you  are  doing.  Even  with  all 
precautions,  it  is  sometimes  next  to  impossible  to  secure  this  indispensable  muscular  re- 
laxation. In  the  healthy  subject  this  test  develops  a  contraction  of  the  quadriceps  ex- 
tensor femoris,  and  causes  an  extension  of  the  leg  or  a  sudden  jerk.  In  a  very  early 
stage  of  posterior  spinal  sclerosis  no  contraction  takes  place. 

"  I  would  also  call  attention  to  the  occasional  occurrence  of  reflex  movements  of  the 
thigh,  produced  by  contraction  of  the  iliac  group  of  muscles  during  the  knee  test.  I  have 
an  example  of  this  distant  reflex  action  in  a  typical  case  of  sclerosis  of  the  posterior  col- 
umns, in  which  the  quadriceps  does  not  contract  at  all. 

"While  claiming  very  great  diagnostic  value  for  this  negative  symptom,  I  would  not  bo 
understood  as  attaching  pathognomonic  significance  to  it,  as  we  all  know  that  there  are  a 
few  seemingly  healthy  individuals  in  whom  the  patellar  tendon  reflex  is  lacking,  and  also 
that  there  are  other  diseases  which  diminish  or  abolish  it.  Indeed,  I  may  say  that  I  rec- 
ognize no  pathognomonic  symptom,  and,  even  in  attempts  to  push  diagnosis  to  an  extreme 
delicacy,  would  urge  that  reliance  be  placed  on  the  grouping  of  symptoms,  rather  than  on 
any  one  of  the  signs,  however  constant  and  important  it  may  appear. 

"  Physiologically  analogous  to  this  condition  of  loss  of  tendinous  reflexes  is  the  flabby 
state  of  the  muscles  in  the  affected  parts.  This  is  not  due  to  any  positive  atrophy,  as 
electrical  tests  show  us  marked  departure  from  the  normal  reactions,  but  to  impairment 
of  what  physiologists  call  muscular  tonus — a  state  of  partial  contiaction  or  tension  of 
muscles,  which  is  kept  up  by  the  inevitable  and  continued  excitation  of  the  cutaneous  nerves 
by  air,  clothing,  surrounding  objects,  etc.,  acting  in  a  reflex  way  through  the  spinal  cord. 
It  has  been  recently  claimed  that  this  loss  of  muscular  tonus  was  the  most  important  factor 
in  the  production  of  the  ataxic  movements  which  characterize  the  second  stage  of  the  disease. 

"  The  vesical  and  rectal  reflexes  are  diminished  in  posterior  spinal  sclerosis.  Slow, 
irregular  micturition  is  complained  of  by  most  patients,  in  the  first  stage  and  in  the  sec- 
ond. We  usually  micturate  without  using  much  volition,  but  the  tabetic  patient  is  obliged 
to  strain  and  to  try  hard  to  pass  water.  Defecation  is,  like  micturition,  a  semi-voluntary 
act,  and  in  the  late  first  stage  of  the  disease  in  question  constipation  becomes  more  and 
more  marked,  and  that  through  loss  of  the  automatic  or  reflex  action  of  the  rectum  and 
adjacent  muscles. 

"  The  sexual  act  is,  in  my  experience,  frequently  impaired  and  sometimes  almost  lost 
before  the  second  stage  sets  in.  The  acts  of  erection  and  emission  are  usually  brought 
about  in  a  reflex  manner  by  irritation  of  the  skin  and  mucous  membrane  of  the  genitals. 
As  a  result  of  diminished  spinal  reflex  action  we  have  imperfect  erections,  and  either 


I 


SYSTEMATIC  LESIONS  OF  KINESODIG  SYSTEM.         325 

the  posterior  columns  of  the  spinal  cord  have  sustained  the 
physiological  experiments  and  deductions  as  regards  the  prob- 
able function  of  these  parts.  We  have  found  that  sensation 
is  affected  in  various  ways  and  degrees  ;  that  coordination  of 
muscular  movement  is  interfered  with  in  the  advanced  stages 
of  the  destructive  process  ;  and,  finally,  that  the  reflex  func- 
tion of  the  spinal  cord  is  impaired,  when  the  sensory  nerves 
become  incapable  of  properly  transmitting  their  impulses  to 
the  motor  cells  of  the  cord. 

Several  theories  have  been  advanced  to  explain  the  devel- 
opment of  ataxic  symptoms,  all  of  which  will  help  to  fix  some 
anatomical  point,  previously  mentioned,  forcibly  in  your  mem- 
ories.    These  theories  may  be  thus  enumerated  : 

1.  That  the  destruction  of  the  commissural  fibers  which 
connect  the  different  segments  of  the  cord  causes  ataxia. 

2.  That  the  tonic  action^  which  is  claimed  to  be  normally  ex- 
erted by  the  spinal  cord  upon  the  muscular  tissues  of  the  body, 
is  impaired  ;  hence,  a  certain  unnatural  relaxation  of  some  parts 
exists,  which  induces  irregularity  of  muscular  movements. 

3.  That  the  condition  of  anaesthesia,  which  is  probably  pres- 
ent in  the  muscular  tissues  as  well  as  in  the  skin,  destroys  the 
so-called  '''muscular  sense "/  hence,  the  patients  can  not  prop- 
erly guide  the  contractions  of  muscles. 

"SYSTEMATIC  LESIONS"   OF  THE   "KINESODIG   SYSTEM." 

As  has  been  -stated  in  the  anatomical  description  of  the 
spinal  cord,  the  kinesodic  or  motor  regions  of  the  cord  include 

piGmature  emission,  or,  what  is  more  common,  I  believe,  very  slow  production  of  the 
orgasm,  and  impossibility  of  repetition  within  a  reasonable  time. 

"  Some  writers  admit  abnormally  great  sexual  power  in  the  early  stage  of  tabes,  but  I 
am  not  sure  to  have  met  with  more  than  one  or  two  cases  in  which  this  seemed  to  be  the 
ease.  In  one  of  the  patients,  a  female,  I  became  convinced  that  her  extraordinary  ca- 
pacity for  sexual  intercourse  was  not  in  a  strict  sense  pathological  or  pre-tabetic,  but  had 
Ijeen  marked  in  one  shape  or  another  from  childhood. 

"  It  seems  reasonable  at  the  present  time  to  advance  this  general  proposition :  that,  in 
1  losterior  spinal  sclerosis,  the  various  reflex  actions  performed  by  means  of  those  portions 
of  the  cord  which  are  the  seat  of  sclerosis  are  diminished  or  lost ;  or,  to  put  it  in  another 
way  more  useful  for  practice,  it  may  be  said  that  the  limitations  of  loss  of  reflex  action  in 
different  parts  of  the  body  accurately  indicate  the  limits  of  sclerosis  in  the  posterior  scn- 
r  ory  apparatus  in  the  spinal  axis." 
23 


I 


326  THE  SPINAL   COED. 

the  columns  of  Tiirck '  (called  also  the  "  direct  pyramidal 
fasciculi  " ),  the  anterior  root  zones,  the  anterior  portion  of  the 
lateral  columns,  and  the  posterior  portion  of  the  lateral  col- 
umns (called  also  the  ** crossed  pyramidal  fasciculi").  As 
indicated  in  the  table  of  diseases  of  the  spinal  cord,'  several 
distinct  and  separate  affections  of  these  component  parts  may 
exist,  each  of  which  presents  some  symptoms  which  are  spe- 
cially diagnostic. 

When  we  review  the  points  mentioned  as  to  the  func- 
tions of  the  kinesodic  system,  we  should  expect  to  find  that 
any  lesion  confined  to  the  regions  designated  above  would  be 
manifested  by  disturbances  in  the  motor  functions  of  the  body 
and  by  certain  ''  tropJiic  changes  "/  while  we  would  also  ex- 
pect to  find  an  absence  of  any  disturbance  in  the  sensory  nerves 
or  in  the  coordination  of  movement.  This  is  fully  confirmed 
by  clinical  experience.  In  all  lesions  of  the  kinesodic  system, 
we  are  apt  to  meet  either  muscular  spasm,  muscular  atrophy, 
or  motor  paresis,  or  paralysis  ;  but  we  are  never  confronted 
with  fulgurating  pains,  numbness,  or  anesthesia,  provided 
the  posterior  columns  (the  sesthesodic  system)  be  not  simulta- 
neously involved.  In  order  to  appreciate  the  points  of  diag- 
nosis of  the  different  forms  of  systematic  lesions  which  may 
affect  the  anterior  half  of  the  cord,  it  will  be  necessary  to  dis- 
cuss, in  a  general  way,  the  special  symptoms  of  each. 

SCLEROSIS   OF  THE   COLUMNS   OF  TURCK. 

The  columns  of  Tiirck  ("  the  direct  pyramidal  fasciculi  '*) 
are  affected  with  sclerosis,  either  separately  and  alone,  or  in 
connection  with  similar  changes  in  the  postero-lateral  columns 
(''the  crossed  pyramidal  fasciculi").  What  its  producing 
causes  are  is,  as  yet,  not  thoroughly  understood.  We  simply 
know,  from  pathological  investigation,  that  sclerosis  of  the 

^  See  page  298  of  this  volume. 

*  Tiirck  may  be  justly  considered  as  the  pioneer  in  the  investigation  of  systemntie 
spinal  Imons,  since,  as  early  as  1851,  he  recognized  sclerosis  of  the  motor  columns  of  the 
cord  and  the  crossed  effect  of  brain  lesions  upon  the  motor  columns.  ^tUich  valuable  re- 
search has  since  been  performed  by  Vulpian,  Bouchard,  Flechsig,  Scguin,  Charcot,  and 
others. 


SCLEROSIS  OF  THE  COLUMNS   OF  TURCK. 


327 


two  portions  of  the  kinesodic  system  mentioned  is  liable  to 
occur  simultaneously,  although  they  may  be  individually 
affected.  AVe  also  know  that  disease  of  the  motor  tract  of 
the  crus,  above  the  decussation  of  the  motor  nerves  in  the  me- 
dulla, as  well  as  lesions  in  the  nucleus  caudatus,  the  internal 
capsule,  the  lobulus  para-centralis,  and  the  motor  regions  of 
the  cortex,  often  causes  what  is  termed  ''  secondary  degenera- 
tion ' '  throughout  the  motor  tract  of 
the  spinal  cord  for  its  entire  length  ; 
hence,  this  condition  of  the  motor 
columns  may  be  the  late  result  of 
some  preceding  brain  lesion,  and  is 
often  confined  to  one  lateral  half  of 
the  cord  (most  commonly  on  the  half 
opposite  to  the  seat  of  the  exciting 
lesion  in  the  brain).  The  accompa- 
nying diagram,  w^hich  illustrates 
the  course  of  the  fibers  in  the  me- 
dulla oblongata,  will  explain  why 
the  symptoms  produced  by  de- 
scending degeneration  of  the  motor 
columns  of  the  cord  are  not  always 
present  upon  the  opposite  side  of 
the  body  to  that  of  the  brain  lesion 
which  produced  it,  since  it  shows 
that  some  of  the  fibers  of  the  cord 
do  not  decussate. 

This  diagram  shows  that  the 
fibers  of  the  medulla  decussate  be- 
fore entering  the  spinal  cord,  for 
the  most  part,'  but  that  a  certain 
proportion  of  the  fibers  pass  in  a 
direct  line  from  the  encephalon  to 
the  cord.  The  figures  (shown  at 
the  bottom  of  the  diagram)  indicate  the  relative  proportion 


Fig.  122. — A  diagram  to  show  the  de- 
cussation of  motor  nerve  Jihei's  in 
the  medulla  oblongata.  (After 
Flechsig  and  Seguin.) 

P.  v.,  pons  Varolii ;  M.  O.,  medulla 
oblongata ;  0,  olivary  body ; 
A.  P.,  anterior  pyramid  ;  D,  de- 
cussation; S.  C,  spinal  cord. 
The  direct  and  crossed  bur.- 
dles  vary  very  much  in  size,  as 
shown  in  the  following  ratios  of 
crossed  and  direct:  (100  :  00), 
(92  :  8),  (84  :  16),  (TO  :  30;, 
(52  :  48),  (35  :  65),  (10  :  90). 


^  Much  of  our  present  knowledge  upon  this  point  is  due  to  the  researches  of  Flechsig  in 
1867,  and  to  those  of  Bouchard  in  1866,  made  in  connection  with  Vulpian  and  Charcot. 


328  THE  SPINAL   CORD. 

between  the  direct  and  the  decussating  fibers,  which  have 
been  found  in  different  instances.  Now,  as  this  "secondary 
degeneration"  (caused  by  lesions  of  the  encephalon)  follows 
the  individual  nerve  fibers,  the  effects  would  be  manifested, 
for  the  most  part,  upon  the  opposite  side  of  the  body,  since 
most  of  the  fibers  decussate  ;  but  some  nerve  fibers,  which  do 
not  decussate,  w^ould  be  impaired  on  the  same  side  of  the  spi- 
nal cord  as  the  existing  brain  lesion.  Thus  we  are  enabled  to 
explain  spinal  symptoms  on  'both  sides  of  the  hody^  when 
preceded  by  a  cerebral  lesion ;  although  the  spinal  manifes- 
tations are  usually  detected  on  the  side  opposite  to  the  excit- 
ing cause.  The  varying  proportion  of  these  direct  fibers  to 
those  which  decussate  will  explain  why  this  secondary  degen- 
eration may  be  followed  by  symptoms  confined  entirely  to 
one  side  of  the  body,  or,  again,  affecting  both  sides. 

You  are  probably  wondering  how  it  is  possible  to  tell 
when  this  slowly  progressing  degeneration  of  the  columns  of 
Tiirck,  or  of  the  postero-lateral  columns,'  is  present.  When 
an  attack  of  hemiplegia  has  occurred,  you  have  probably 
been  able  to  decide  early  whether  it  is  of  cerebral  or  spinal 
origin  ;  since,  if  cerebral,  it  will  probably  affect  the  side  of 
the  body  opposite  to  the  seat  of  the  lesion  within  the  brain, 
and  other  points  in  the  history  will  probably  confirm  this  as 
the  exciting  cause.  Some  time  after  the  attack  of  hemiplegia, 
however,  you  will  notice  that  the  paralyzed  muscles  are  be- 
coming more  or  less  rigid,  and  that  a  state  of  contracture  is 
developing.  Now,  it  is  this  point  in  the  case  that  should  in- 
dicate to  your  minds  the  fact  that  a  progressive  descending 
degeneration  of  the  spinal  cord  is  taking  place,  and  you  can 
safely  expect  to  find  sclerosis  of  the  anterior  and  postero-lat- 
eral columns  at  the  autopsy. 

In  some  cases  the  contracture  of  paralyzed  muscles,  after 
an  attack  of  hemiplegia,  is  accompanied  by  an  atrophy  of  the 
paralyzed  and  rigid  muscles ;  so  that  their  volume  becomes 
much  more  extensively  impaired  than  would  ensue  from  sim- 

'  Our  present  knowledge  leads  us  to  infer  that  the  anterior  and  lateral  columns  pos- 
sess a  similarity  of  function. 


SCLEROSIS  OF  THE  LATERAL   COLUMI^S.  329 

pie  disuse.  In  this  event,  you  may  be  justified  in  suspecting 
that  the  anterior  horns  of  the  gray  matter  of  the  spinal  cord 
are  becoming  diseased,  a  condition  to  which  the  term  "  polio- 
myelitis," or  ''myelitis  of  the  anterior  horns,"  may  be  found 
applied  in  treatises  upon  nervous  diseases.  This  will  be  con- 
sidered in  detail  in  a  subsequent  lecture. 

SCLEROSIS   OF   THE   LATERAL   COLUMN'S    ('^  TETAJs^OID   PARAPLEGIA  " — 
"  SPASMODIC   TABES  "  ). 

The  lateral  columns  (including  the  whole  of  the  mass  of 
white  substance  found  at  the  sides  of  the  spinal  cord)  may  be 
diseased,  either  as  a  primary  lesion,  following  cold,  damp- 
ness, over-exertion,  and  syphilis,  or  as  a  part  of  a  secondary 
morbid  process  (chiefly  in  connection  with  polio-myelitis). 
In  1875  the  name  of  ''spastic  spinal  paralysis"  was  applied 
to  this  condition  by  Erb,'  and  in  1876  Charcot'  described  it 
under  the  head  of  "spasmodic  tabes."  You  will,  therefore, 
And  it  described  under  both  of  these  names,  although  I  prefer 
the  name,  applied  to  it  by  my  friend  Professor  Seguin,  "  teta- 
noid paralysis  or  paraplegia,"  since  to  the  common  mind  it 
best  conveys  the  idea  of  its  symptomatology. 

As  this  lesion  is  often  combined  with  myelitis  of  the  ante- 
rior horns  of  gray  matter,  as  mentioned  above,  and  since  such 
degeneration  of  the  anterior  horns  is  apt  to  affect  the  "trophic 
function"  of  the  cord,  Charcot  has  applied  to  this  complex 
systematic  affection  of  the  cord  the  term  "  amyotrophic  lateral 
sclerosis."  A  peculiarity  of  sclerosis  of  the  lateral  columns 
of  the  cord,  whether  complicated  with  disease  of  the  anterior 
horns  or  not,  is  that  hoth  sides  of  the  spinal  cord  are  nearly 
always  involved  at  the  same  time  ;  hence,  the  occurrence  of 
paraplegia  is  more  strongly  diagnostic  of  this  affection,  pro- 
vided other  symptoms  of  value  exist,  than  if  hemiplegia  be 
present.  I  shall  use  the  term  "tetanoid  paraplegia,"  there- 
fore, in  preference  to  the  other  names  suggested  by  the  au- 
thors quoted,  in  describing  the  symptoms  which  are  diag- 
nostic of  this  affection. 

^  Op.  cit.  2  Qp^  cit. 


I 


330  THE  SPINAL   CORD. 

When  the  sclerosis  of  the  lateral  columns  affects  the  cervi-  ^ 
cal  enlargement  of  the  spinal  cord  (where  the  nerves  to  the 
upper  extremities  are  given  off),  the  symptoms  appear  hrst  in 
the  hands.  The  affected  parts  have  a  peculiar  sense  of  formi- 
cation, like  the  creeping  of  ants  over  the  part.  They  undergo  I 
rapid  atrophy  (if  the  anterior  horns  are  affected '),  causing 
the  hands  to  become  bony  from  disappearance  of  the  inter- 
ossei  muscles,  and  the  parts  become  simultaneously  para- 
lyzed. Soon  a  contracture  of  the  paralyzed  muscles  develops, 
producing  the  so-called  '^claw-hand  deformity."  The  lower 
limbs  become  at  first  paretic,  but  gradually  develop  a  para- 
lyzed and  contractured  condition  ;  although  the  contractured 
state  of  the  muscles  is  very  much  more  apparent  when  the 
patient  stands  and  attempts  to  walk  than  when  lying  in  bed, 
since  the  rigidity  almost  disappears  when  in  the  recumbent 
position.  If  the  lesion  extend  upward  to  the  region  of  the 
motor  bulbar  nerves,  the  symptoms  of  glosso-labio-laryngeal 
paralysis ""  may  be  developed,  in  addition  to  the  other  sym 
toms  described.  The  muscles  of  the  legs  do  not  generall 
waste,  and  the  bladder  and  rectum  are  not,  as  a  rule,  pa; 
lyzed.  No  evidences  of  anaesthesia  can  be  usually  discoverei 
in  the  regions  affected. 

In  tetanoid  paraplegia,  there  is  a  marked  increase  in  th 
reflex  excitability  of  the  affected  parts.     It  is  to  this  increase 
in  all  the  reflex  movements  that  the  peculiar  gait  of  this  cl 
of  patients  may  be  attributed.     Thus,  the  increased  action  o: 
the  adductor  muscles  tends  to  make  the  legs  almost  cross  eac 
other  in  walking ; '  the  excessive  action  of  the  muscles  of  th 
calf  raises  the  heel,  and  the  legs  move  with  a  stiffness  whic 
makes  a  contrast  with  the  normal  act  of  walking.     In  the  la 
stages  of  this  affection,  when  the  patient  becomes  bediidde 


*  A  complex  condition,  termed  by  Charcot  "  amyotrophic  lateral  sclerosis."     The  ] 
ticnt  at  first  walks  with  a  cane,  then  with  crutches,  and  later  on  requires  an  attendant. 

*  The  symptoms  of  this  affection  (Duchcnne's  disease)  have  been  given  in  detail  ii 
connection  with  the  hypo-glossal  nerve.  The  reader  is  referred  to  page  279  of  thU 
volume. 

3  When  both  the  lower  limbs  arc  affected  by  lesions  of  the  lateral  columns  of  tl 
cord,  the  legs  frequently  become  interlocked  at  every  attempt  to  walk. 


TETANOID  PARAPLEGIA.  33I 

tlie  increased  reflex  excitability  causes  tlie  legs  to  become 
semi-flexed  and  addiicted,  and  the  muscles  are  sensibly  hard- 
ened. It  is  a  clinical  point  of  some  value  that  the  muscles 
affected  with  tetanoid  paraplegia  retain  their  normal  size,  nu- 
trition, and  electrical  reactions  (provided  that  the  anterior 
horns  are  not  diseased).  This  condition  is  quite  commonly 
met  with  in  children  ; '  and  the  little  sufferers  can  not  often 
stand  or  walk,  from  the  spasmodic  action  of  the  muscles  of  the 
legs.  In  adults,  as  a  further  evidence  of  the  increased  reflex 
excitability  of  parts,  the  act  of  passing  the  urine  or  faeces  be- 
comes one  which  requires  the  patient  to  hurry  with  all  possible 
speed,  in  order  to  avoid  a  sudden  and  involuntary  evacuation. 
Now,  the  absence  of  anaesthesia,  of  numbness,  and  of  ful- 
gurating pains,  will  easily  assist  you  to  diagnose  between  a 
case  of  disease  of  the  posterior  columns  and  that  of  the  lat- 
eral columns  of  the  cord,  although  the  peculiarity  of  gait 
may  for  a  while  confuse  you.  The  increase  in  the  "patellar 
reflex  "  ^  and  the  actual  loss  of  power  of  individual  muscles 
will  also  assist  you  in  the  diagnosis  ;  while  in  tetanoid  para- 
plegia the  muscles  are  stiffened,  especially  when  standing  or 
walking,  sensations  are  not  delayed,  and  coordination  of 
movement  is  normally  performed. 

MYELITIS    OF    THE    ANTERIOR    HORN^S    ("ATROPHIC    SPIITAL 
PARALYSIS  "). 

As  shown  in  the  table '  of  diseases  which  may  affect  the 
kinesodic  system  of  the  spinal  cord,  the  anterior  horns  of  gray 
matter  may  be  the  seat  of  degeneration.  As  in  all  other  le- 
sions of  the  motor  tract  of  the  cord,  the  symptoms  of  this 
affection  are  conflned  to  motor  phenomena,  and  characterized 
by  the  absence  of  sensory  effects  (anaesthesia,  numbness, 
etc.) ;  but,  in  addition  to  the  motor  phenomena,  certain  tro- 

^  These  children  are  often  microcephalic  or  idiotic ;  hence  the  symptoms  may  be  due 
to  an  incomplete  development  of  the  motor  tract  of  the  spinal  cord.  It  is  stated  by  Se- 
g'jin  that  circumcision  can  not  be  considered  as  a  curative  measure  in  all  cases,  since 
Jewish  children,  circumcised  at  birth,  have  been  frequently  seen  by  him  with  typical  evi- 
dences of  this  disease. 

2  See  page  323  of  this  volume.  ^  See  page  315  of  this  volume. 


332  THE  SPINAL   CORD. 

pMc  changes  become  prominently  developed,  which  are  of 
special  value  to  the  diagnostician. 

In  this  lesion  we  find,  after  death  has  occurred,  that  the 
motor  cells  of  the  cord  have  undergone  atrophy  (due,  prob- 
ably, to  an  acute  inflammatory  degeneration  associated  with 
pigmentation  of  the  parts),  and  that  the  anterior  roots  of  the 
spinal  nerves  have  likewise  undergone  a  fatty  metamorphosis. 
The  condition  may  be  of  three  distinct  types,  which  are  called 
the  acute,  sub-acute,  and  chronic  varieties,  and  each  presents 
certain  characteristic  symptoms.  The  tenn  "'poUo-myeUtis^' 
is  frequently  used  as  a  synonym  for  this  change  in  the  ante- 
rior horns. 

The  acute  form  is  manifested  by  the  presence  of  a  fever, 
either  of  the  continued  or  remittent  type,  which  is  usually  ac- 
companied by  pains  and  a  sense  of  numbness  in  the  limbs. 
As  the  fever  subsides,  usually  in  the  course  of  several  days, 
an  extensive  paralysis  is  suddenly  developed.  This  paralysis 
may  affect  both  arms  and  both  legs,  the  legs  alone,  or,  pos- 
sibly, only  one  of  the  four  extremities  ;  it  may  occasionally  be 
a  hemiplegia,  if  one  side  of  the  cord  is  alone  involved.  In  a 
longer  or  shorter  space  of  time,  this  paralysis  gradually  dimin- 
ishes ;  the  bladder  and  rectum  remain  unimpaired  throughout 
the  attack  of  paralysis ;  no  anaesthesia  or  numbness  can  be 
detected  in  the  paralyzed  parts  ;  and  there  is  no  tendency  to 
the  development  of  bed-sores.  If  you  test  the  paralyzed 
limbs  for  reflex  movements,  you  will  usually  find  them  totally 
abolished.'  If  you  apply  the  faradic  current,  the  muscles 
will  fail  to  respond  ;  but,  when  the  constant  current  is  used, 
you  will  notice  a  slow  contraction,  and  certain  variations  in 
the  usual  formulae  of  galvanic  reaction  will  stamp  the  condi- 
tion as  one  of  degeneration.'    What  these  formulae  are  can  be 

'  This  is  not  always  the  case,  as  the  reflex  movements  arc  oftentimes  only  decreased 
in  frequency  and  force. 

2  "  Remarkably  distinct  evidences  of  the  dei^enerative  reaction  to  electricity  arc  ob- 
tained from  the  second  to  the  tenth  week.  The  nerve  trunks  supplying  the  paralyzed 
muscular  groups  lose  their  excitability  to  faradism  and  galvanism,  and  these  wasting 
muscles  react  only  to  galvanism,  and  their  reaction  formula  is  altered  from  the  normal ; 
in  general  terms,  we  may  say  that  An  c  c  =  Ka  c  c,  or  even  An  c  c  >  Ka  c  c;  and  all  con- 
tractions are  slow  and  wave-like."     (E.  C.  Scguin,  "Med.  Uecord,"  187S.) 


MYELITIS  OF  THE  A^^TERIOR  HORNS.  333 

easily  found  in  any  of  the  special  treatises  on  the  treatment 
and  diagnosis  of  nervous  affections.  JN'ow,  in  this  type  of 
myelitis,  you  will  not  have  to  wait  long  to  decide  as  to  its 
character.  In  a  few  days  or  weeks  the  muscles  of  the  para- 
lyzed limbs  will  show  a  rapid  wasting,  since  the  muscles  are 
undergoing  atroiohy ;  and  this  wasting  is  markedly  progres- 
sive, since  the  change  in  the  muscles  continues  to  extend  until 
a  most  characteristic  and  permanent  deformity  results,  pro- 
vided that  recovery  does  not  occur. 

This  condition  of  the  cord  is  frequently  associated  with 
sclerosis  of  the  lateral  columns  ;  hence,  it  is  not  infrequent  to 
observe  a  state  of  contraction  in  the  paralyzed  muscles,  which 
lasts  in  a  varying  degree,  until  the  atrophy  of  the  contractured 
muscles  destroys  their  power  of  producing  deformity.  These 
contractions  are  not  inevitably  permanent,  if  present  in  the 


Fig.  Vlo.— Atropine  spinal  paralysis,  uith  contracture.     (Hammond.) 

early  stages  of  the  disease,  as  they  may  totally  disappear  in 
t  exceptional  cases ;  but  they  usually  return  with  increased 
deformity  as  the  disease  progresses. 

In  those  cases  of  so-called  'infantile  spinal  paralysis,"  and 
in  similar  cases  affecting  the  adult,  a  non-febrile  "cariety  of 
this  affection  may  be  met  with,  where  the  disease  begins  with 
no  initial  symptoms,  but  where  the  paralysis  and  all  subse- 
quent symptoms  mentioned  above  are  developed  suddenly. 


334  THE  SPINAL   CORD. 

The  chronic  form  of  myelitis  of  the  anterior  horns  is  sel- 
dom to  be  diagnosed  from  progressive  muscular  atrophy.-  It 
is  claimed  that  the  severe  neuralgic  pains  which  accompany 
the  wasting  process  of  the  former  are  diagnostic  between  the 
two  affections,  and  that  the  degeneration  of  the  affected  parts 
does  not  assume  ih^  fibrillary  oix  fascicular  character  of  true 
progressive  atrophy,  dependent  upon  changes  confined  to  the 
ganglion  cells  of  the  spinal  cord,  but  the  distinction  is,  in  my 
experience,  a  difficult  one. 

The  condition  of  polio-myelitis  tends,  as  a  rule,  to  progress 
upward  along  the  spinal  cord,  and  thus  often  reaches  the  me- 
dulla oblongata.  The  symptoms  which  are  then  produced  in- 
clude those  of  paralysis  and  atrophy  of  the  tongue,  difficult 
deglutition,  impairment  of  speech,  and  a  nasal  quality  of  the 
voice,  due  to  the  paralysis  of  the  soft  palate.  The  expression 
of  the  face  is  greatly  altered  by  paralysis  of  the  orbicularis 
oris  muscle,  which  creates  an  apparent  increase  in  the  width 
of  the  mouth  ;  and,  after  laughing  or  weeping,  the  mouth  re- 
mains open  for  an  unusual  period,  and  thus  favors  the  escape 
of  saliva. 

PKOGRESSIVE     MUSCULAR    ATROPHY     (DEGENERATION     OF    THE    GAN- 
GLION CELLS   OF  TIEE  ANTERIOR  HORNS). 

Degeneration  of  the  ganglion  cells  of  the  anterior  horns  of 
the  cord  is  pathologically  distinguished  from  the  condition  just 
described,  since  the  results  of  the  former  were  of  an  inflam- 
matory character,  while  the  latter  is  a  purely  degenerative 
process  of  primary  origin.  The  former  was  rapid  in  its  effects  ; 
this  disease  is  slow,  since  the  ganglion  cells  undergo  molecular 
disintegration.  We  may  expect  to  find,  at  the  autopsy  of 
such  a  case,  the  cells  changed  into  a  granular  condition,  and 
more  or  less  destroj^ed  ;  while,  in  extreme  cases,  the  anterior 
horns  of  gray  matter  of  the  affected  pai*t  may  be  utterly 
destitute  of  these  cells. 

It  is  this  pathological  change  that  creates  the  train  of 
symptoms  called  '*  progressive  muscular  atrophy."  The  mus- 
cles, supplied  by  nerves  connected  with  the  seat  of  degener- 


PROGRESSIVE  MUSCULAR  ATROPHY. 


335 


ation,  begin  to  show  a  slowly  developing  atrophy  of  certain 
fibers  or  bundles,  while  other  parts  of  the  muscle  may  ap- 
pear perfectly  normal ;  thus  it  may  take  months  for  an  entire 
muscle  to  become  completely  wasted, 
the  muscle  showing  during  its  con- 
traction the  gradual  atrophy  of  cer- 
tain parts.  This  disease  seems  to  exist 
most  commonly  in  the  muscles  of  the 
hand,  thighs,  and  chest,  and  a  symme- 
try '  in  its  development  is  a  character- 
istic feature.  It  is  seldom  associated 
with  any  sensory  symptoms.  In  the 
rarest  cases  will  you  be  able  to  detect 
the  existence  of  pain  ; "  and  symptoms 
of  anaesthesia  are  wholly  absent.  An- 
other point  which  will  assist  you  in 
diagnosis  is  the  absence  of  paralysis ; 
although  the  affected  muscles  may  show 
a  loss  of  power  in  proportion  to  the  ac- 
tual destruction  of  muscular  tissue.  If 
you  apply  the  faradic  current  to  the 
affected  muscles,  you  will  find  that  they 
respond  to  its  influence  in  exact  pro- 
portion to  the  extent  of  the  degenera- 
tion, so  that  the  unaffected  fasciculi 
will  be  thrown  into  contraction.  This 
is  in  marked  contrast  to  the  effect  of 
the  faradic  current  ux)on  the  muscles  in 
the  case  of  myelitis  of  the  anterior 
horns,  where  the  muscles  failed  to  re- 
spond in  their  entirety,  even  before  they  shovf ed  any  evidence 
of  atrophy. 

The  muscles  which  are  undergoing  the  early  changes  of 


Fig.  124. — Progressive  mus- 
cular atrophy  of  upper 
extremity.    (Hammond.) 


'  The  atrophy  affects  parts  which  are  not  only  symmetrical,  but  homologous.  It  is 
common  to  see  both  shoulders  simultaneously  atrophied,  or  the  arms  and  thighs,  or  the 
forearms  and  the  legs. 

2  Hammond  states  that  pain  is  perceived  after  exertion,  but  he  attributes  it  to  muscular 
fatio-ue  rather  than  to  central  causes. 


336 


THE  SPIXAL   CORD. 


this  wasting  are  the  seat  of  what  are  called  fibrillary  contrac- 
tions ^    These  are  produced  by  the  involuntary  rapid  contrac- 


FiG.  125. — Progressive  muscular  atropJiy.     Age  of  patient^  forty-Jive  yean 

reich.) 


(From  Fried- 


tions  of  fasciculi  of  fibers  in  a  muscle.  Sometimes  a  patieni 
is  covered  with  them.  Some  years  ago,  these  fibrillary  con- 
tractions were  held  to  be  pathognomonic,  but  I  can  assure 
you  that  this  is  not  so,  as  they  may  be  observed  in  lead  palsy, 

*  These  peculiar  twitchings  give  the  appearance  of  something  alive  being  underneath 
the  skin.  Hammond  states  that  "  they  can  always  be  excited  by  a  smart  tap  of  the  fin- 
ger upon  the  atrophied  muscle." 


PEOGRESSIVE  MUSCULAR  ATROPHY.  337 

in  conditions  of  neurasthenia,  and  in  simple  paralysis.  In- 
deed, many  years  ago  Professor  Schiff,  now  of  Geneva,  showed 
rhat  muscles  separated  from  their  motor  nerves  were  prone  to 
.show  fibrillary  contractions. 

The  hall  of  the  tliumh  is  often  the  starting-point  of  this 
disease.  For  some  reason,  the  muscles  of  the  foot  are  not  af- 
fected in  the  same  proportion  in  those  cases  where  the  lower 
extremity  is  involved  as  the  hand  is  in  cases  affecting  the 
ux)per  extremity.  In  some  instances,  every  muscle  in  a  region 
l)ut  one  may  be  atrophied,  and  that  one  seem  to  remain  per- 
fectly normal.  If  you  use  a  surface  thermometer,  you  will 
generally  detect  a  fall  of  temperature  over  the  affected  mus- 
cles.' A¥hen  the  respiratory  muscles  become  involved,  death 
may  be  produced  from  imperfect  performance  of  that  func- 
tion. The  disease  seems  to  affect  males  rather  than  females, 
and  to  be  most  frequent  during  middle  life.  It  is  sometimes 
associated  with  a  congenital  predisposition.'* 

The  muscles  of  the  thigh  are  frequently  affected  with 
atrophy,  following  degeneration  of  the  ganglion  cells  of  the 
anterior  horns  of  the  spinal  gray  matter.  This  causes  not 
only  a  very  marked  deformity  (since  the  calf  may  even  ex- 
ceed the  thigh  in  its  circumference),  but  a  peculiarity  of  gait 
is  thus  produced  which  differs  from  those  described  in  con- 
nection with  locomotor  ataxia,  tetanoid  paraplegia,  and 
paresis. 

If  the  extensor  muscles,  which  are  situated  upon  its  an- 
terior portion,  are  atrophied,  the  foot  can  not  be  carried  for- 
ward in  the  normal  manner,  if  at  all ;  while  the  leg  and  foot 
can  not  be  raised,  if  the  flexor  muscles  of  the  knee  joint  be 
impaired  by  an  atrophy  confined  to  the  posterior  aspect  of 
the  thigh,  thus  compelling  the  psoas  and  iliacus  muscles  to 
lift  the  weight  of  the  entu-e  upper  extremity  by  using  the 
pelvis  as  a  fixed  point. 

^  Hammond  reports  this  fall  in  temperature  as  often  reaching  five  degrees  below  the 
normal  standard. 

"  See  the  careful  investigations  made  by  Hammond,  and  reported  by  him  in  his  excel- 
lent work,  "  A  Treatise  on  the  Diseases  of  the  Nervous  System."  New  York  :  D.  Apple- 
ton  &  Co.,  1876. 


338  THE  SPINAI^   CORD. 

Distortions  of  the  affected  members  often  accompany  the 
condition  of  progressive  muscular  atrophy.  These  are  to  be 
accounted  for  by  the  fact  that  a  simultaneous  impairment  of 
all  the  muscles  seldom  occurs,  and  those  antagonistic  to  the 
ones  affected  tend  to  produce  an  abnormality  of  attitude  in 
the  part  upon  which  they  both  acted  in  health. 

CENTRAL  MYELITIS. 

Among  the  diseases  of  the  kinesodic  system  may  be  men- 
tioned the  condition  known  as  "central  myelitis."  In  this 
affection,  the  gray  matter  of  the  cord  is  the  seat  of  a  chronic 
type  of  inflammation  in  its  central  portion ;  hence,  it  may 
involve  either  the  kinesodic  or  the  sesthesodic  system.  The 
inflammatory  process  may  extend  to  the  anterior  horns,  or 
may  create  compression  of  the  cord,  in  almost  any  portion,  by 
the  exudation  which  results.  The  symptoms  of  this  disease 
must,  therefore,  of  necessity,  vary  with  the  seat  of  the  patho- 
logical changes,  and,  in  some  cases,  be  very  obscure  and  appa- 
rently confusing  to  the  diagnostician.  We  may  have  the  man- 
ifestations confined,  for  a  time,  to  the  sensory  nerves,  possibly 
accompanied  by  pain,  numbness,  anaesthesia,  formication,  etc. 
Gradually  certain  manifestations  will  appear  in  the  motor 
nerves,  and  paralysis  of  certain  muscles  and  possible  atrophy 
may  be  developed.  The  reflex  action  may  be  increased  in 
some  parts  and  diminished  in  others,  according  to  the  portion 
of  the  gray  matter  involved ;  bed-sores  and  paralysis  of  the 
bladder  and  rectum  may  be  present  in  some  cases,  and  absent 
in  others ;  the  legs  may  be  anaesthetic,  and  at  the  same  time 
paralyzed  ;  so  may  the  arms,  without  the  legs,  or  both  may  be 
thus  affected  ;  certain  parts  may  have  the  tetanoid  condition 
described  in  a  previous  portion  of  this  lecture  ;  and,  in  fact, 
every  known  combination  of  sensory  and  motor  symptoms 
may  be  present,  complicated  or  uncomplicated  by  the  evi- 
dences of  muscular  rigidity.  You  can  thus  understand  that 
the  disease  is  seldom  recognized  in  its  early  stage,  and,  as  it 
often  takes  years  to  reach  a  full  development,  an  abundant 
opportunity  will  generally  be  afforded  you  for  a  careful  and 


NON-SYSTEMATIC,  OR  ''FOCAL''  LESIONS.  339 

close  analysis  of  the  symptoms  which  are  successively  brought 
to  your  notice/ 


"XON-SYSTEMATIC"    OR    "FOCAL    LESIONS"    OF    THE    SPINAL 

CORD. 

We  have  now  considered,  in  this  course  of  lectures  upon 
the  spinal  cord,  those  lesions  which  are  called  ''systematic," 
since  they  tend  to  extend  upward  or  downward  in  the  same 
column  of  the  cord  without  spreading  laterally ;  and  it  now 
remains  for  us  to  review  such  points  as  pertain  to  those  focal 
or  non-systematic  lesions  which  have  been  enumerated  in  the 
table  of  diseases  of  the  spinal  cord.  It  is  often  possible  and 
of  great  practical  importance  to  the  diagnostician  to  tell  in 
what  region  of  the  cord  the  lesion  is  situated,  and  to  estimate 
the  height  to  which  it  has  progressed.  Of  course,  this  is 
much  easier  in  focal  lesions  than  in  the  systematic,  since  the 
different  columns  of  the  cord  can  then  simultaneously  fur- 
nish symptoms  which  can  be  compared,  and  thus  aid  in  the 
diagnosis.  If  you  will  look  again  at  the  table, ""  to  which  I 
some  time  ago  directed  your  attention,  you  will  perceive  that 
the  focal  lesions  include  traumatisms  (of  all  forms) ;  compres- 
sion of  the  cord  (chiefly  by  bone  and  tumors) ;  transverse  scle- 
rosis of  the  cord ;  transverse  softening  of  the  cord ;  haemor- 
rhage into  the  substance  of  the  cord ;  and,  finally,  certain 
tumors  which  involve  the  cord  itself.  There  are  many  other 
causes  which  might  excite  some  local  lesion,  but  these  are  the 
ones  which  will  most  frequently  come  under  the  notice  of  the 
practitioner. 

Before  we  begin  the  study  of  the  symptoms  produced 
by  lesions  at  different  heights  in  the  spinal  cord,  it  may  be 
well  to  glance  hastily  at  the  drawing  which  I  have  made  for 
YOU  upon  the  blackboard,  copied  from  one  made  by  Seguin 
from  the  text  of  Malgaigne,  which  is  so  simple  and  diagram- 

'  The  valuable  contributions  of  Hallopeau,  in  the  "  Archives  Generales  de  Medecine," 
IS'72,  added  much  to  the  knowledge  of  this  obscure  affection.  Schiippel,  Westphal,  and 
Leyden  have  also  been  prominent  as  investigators  of  this  rather  rare  form  of  disease. 

"^  See  page  3 1 5  of  this  volume. 


340 


THE  SPINAL   CORD. 


matic  as  to  illustrate  certain  points  of  great  clinical  value  and 
importance. 

Now,  if  you  will  look  at  this  diagram,  you  will  perceive 
that  the  line  upon  the  left  represents  the  different  levels  of 


Medulla. 


c   «i 

J—       y 

Us 
a 


Axis.  <^ 

8dC.  V.  <; 

(ith  0.  Y.  <( 

Tth  C  V.  ^ 

2d  D.  V.  <^ 


nth  D  V.  <; 

12th  D.  V.  ^ 

1  L  V.  <^ 

2  L.  V.  <^ 


Hypo-glossal  N. 

Pneumogastric  N. 
Phrenic  N. 

Brachial  plexus. 
Ulnar  nerve. 


Crural  N. 


Sciatic  N. 


Fig.  126. — A  diagram  shovnng  the  relation  of  the  spinous  processes  of  the  vertchrce  to  the 
spinal  nerves  and  spinal  cord.     (Malgaigne  and  Seguin.) 

the  spines  of  the  vertebrae,  and  that  the  special  points  in  the 
cord,  as  well  as  the  points  of  origin  of  certain  of  the  more  im- 
portant nerves,  are  likewise  shown.  You  will  observe  that 
the  hypo-glossal  and  the  pneumogastric  nerves  arise  from  the 
medulla,  which  lies  above  the  level  of  the  axis  ; '  that  the 
phrenic  arises  on  a  level  with  the  spine  of  the  axis  ;  that  the 
brachial  plexus  and  the  ulnar  nerve  are  connected  with  the 

*  This  drawing  illustrates  the  fact  that  the  spines  of  the  respective  vertebrae  do  not 
always  correspond  to  the  level  of  the  nerves  which  escape  from  between  their  pedicles. 


FOCAL  LESIONS  OF  THE  SPINAL    CORD.  341 

cord  in  the  region  of  the  neck  (third  to  sixth  cervical  spines) ; 
that  the  cilio-spinal  center  is  situated  between  the  fifth  cervi- 
cal and  the  second  dorsal  vertebrse  ;  that  the  lumbar  enlarge- 
ment of  the  cord  gives  otf  the  crural  and  sciatic  nerves  at 
(liiferent  points,  and  that  the  space  between  the  eleventh  dor- 
sal and  the  second  lumbar  spines  includes  the  point  of  origin 
of  both  ;  finally,  that  the  spinal  cord  ends  at  the  second  lum- 
bar spine,  although  the  nerves  continue  to  escape  from  the 
spinal  canal  much  below  that  point.  Such  a  diagram  will 
prove  of  constant  service  to  you,  in  following  the  discussion 
of  the  symptoms  of  focal  lesions  situated  at  different  heights 
within  the  spinal  cord. 

We  have  already  studied  the  effects  of  systematic  lesions, 
both  of  the  kinesodic  and  sesthesodic  systems,  and  have 
noticed  how  perfectly  the  physiology  of  the  spinal  cord  is 
confirmed  by  lesions  affecting  the  anterior  or  posterior  por- 
tions of  the  cord  separately.  We  are  now  to  investigate 
tliose  lesions  which,  by  extending  in  a  transverse  direction, 
are  liable  to  be  accompanied  by  symptoms  referable  to  both 
the  sensory  and  motor  portions  of  the  cord.  Of  course,  the 
8ymx)toms  will  be  modified  by  the  extent  of  the  lesion  in  a 
transverse  direction,  so  that  they  may  be  mostly  sensory  or 
motor  ;  but  the  presence  of  both  sensory  and  motor  symp- 
toms is  strongly  diagnostic  of  focal  lesions^  irrespective  of  a 
predominence  of  either,  and  is  never  produced  by  any  sys- 
tematic lesion  of  the  cord,  with  the  one  exception  of  central 
myelitis. 

We  will  start  with  a  general  statement,  as  a  guide  in  our 
study  of  focal  lesions,  which  is  as  follows  :  focal  lesions  usu- 
ally give  rise  to  ^araZ^/^?^  of  motion,  to  an  alteration  in  the 
reflex  excitability  of  the  cord  (usually  an  increase),  and  to 
more  or  less  ancestJiesia,  numbness,  and  pain;  the  bladder 
and  rectum  are  often  paralyzed,  and  a  tendency  to  bed-sores 
is  frequently  produced.  The  first  two  of  these  effects,  and 
also  the  last,  are  due  to  alteration  in  the  kinesodic  system  ; 
the  remaining  ones  are  the  result  of  some  disturbance  to  the 
cGsthesodic  system. 

24 


342  THE  SPINAL   CORD, 

In  studying  focal  lesions  situated  in  different  regions  of 
the  spinal  cord,  we  must  adopt  some  system,  if  we  expect  to 
grasp  the  fine  distinctions  which  can  be  drawn  between  the 
results  of  lesions  of  the  upper  cervical  region,  the  cervical  en- 
largement, the  mid-dorsal  region,  the  region  just  above  the 
lumbar  enlargement,  and,  finally,  the  lumbar  enlargement 
itself.  Most  of  these  distinctions  depend  upon  certain  ana- 
tomical points,  which  your  previous  drill  will  enable  you  to 
appreciate  more  easily  than  if  your  anatomical  knowledge 
had  become  deficient  from  a  lack  of  review. 

FOCAL   LESIOI^   IN   THE   UPPER   CERVICAL   REGION. 

In  this  condition,  hemiplegia  will  be  produced  if  one  lat- 
eral half  of  the  cord  be  alone  affected,  while  paraplegia  will  be 
present  if  the  lesion  extends  transversely  to  both  lateral  halves 
of  the  cord.  The  hemiplegia  or  paraplegia  will  be  complete 
below  the  head,  and  the  entire  body  may  be  rendered  anaes- 
thetic. Since  the  phrenic  nerve  arises  at  this  point,  the  act  of 
respiration  will  be  interfered  with,  creating  dyspnoea  and  hic- 
cough ;  but  the  respiration  will  not  be  arrested,  since  the 
pneumogastric  nerves  continue  to  excite  it,  and  the  auxiliary 
muscles  of  respiration  can  expand  the  chest  without  the  action 
of  the  diaphragm.  Should  the  lesion  be  a  surgical  one  (as  it 
usually  is),  the  respiraiory  center  of  the  medulla  may  be  af- 
fected, and  death  take  place  from  asphyxia ;  but  I  do  not 
think  such  a  result  can  be  explained  as  a  simple  effect  of  pa- 
ralysis of  the  phrenic  nerves  alone.  The  presence  of  the  cilio- 
spinal  center  in  the  lower  cervical  region  may  cause  the  pu- 
pils to  show  an  irregularity,  and  the  face  and  neck  may  mani- 
fest a  marked  increase  of  temperature.'  The  pulse  may  b(^ 
rendered  variable,  from  irritation  of  or  pressure  upon  the  ac- 
celeratory  center  of  the  heart. 

Now,  as  I  have  before  said,  this  type  of  lesion  is  almost  al- 
ways a  surgical  one,  comprising  pressure  from  fracture,  dislo- 
cation, caries,  tumors  of  the  vertebrae,  etc.,  and  these  cases 

'  Sec  page  134  of  this  volume  for  effects  of  blood-vessels  upon  tbe  iris  ;  and  also  pap 
185  for  the  evidences  of  diminished  iritic  reflex. 


FOCAL  LESIONS   OF  THE  CERVICAL  REGION.  343 

seldom  live  long  enough  for  us  to  study  the  effects  of  such  a 
lesion  with  much  detail.  In  those  rare  instances  where  the 
lesion  is  non- traumatic  and  slowly  developed,  the  effects  of 
irritation  have  been  shown  in  a  hiccough  (probably  due  to 
irritation  of  the  phrenic  nerve),  acceleration  of  the  pulse 
(from  irritation  of  the  acceleratory  center  of  the  heart),  and 
dyspnoea  (from  some  interference  with  the  phrenic  nerve  or 
the  nucleus  of  the  pneumogastric  nerve  in  the  medulla) ; 
while  the  paralysis  has  first  appeared  as  a  paretic  condition 
of  the  arms,  then  of  the  chest,  and,  finally,  of  the  lower  limbs. 

FOCAL   LESION^S   OF   THE   CERVICAL   EKLARGEMEN^T. 

This  type  of  lesion  differs  in  its  effects,  if  developed  sud- 
denly or  gradually,  and  also  when  situated  in  the  upper  or  the 
lower  part  of  the  enlargement.  If  the  lesion  be  so  situated  as 
to  create  only  irritation  of  the  cilio-spinal  center,  or  the  ac- 
(^eleratory  center  for  the  heart  (both  of  which  are  in  that  vicin- 
ity), the  effects  will  differ  from  those  due  to  actual  pressure 
upon  or  destruction  of  those  centers.'  In  the  first  instance, 
the  pupils  will  usually  be  dilated  and  the  face  pale,  while 
t  lie  heart  will  be  accelerated ;  in  the  latter,  the  pupils  will 
generally  be  contracted,  the  face  and  neck  flushed,  and  the 
pulse  retarded.  The  effects  will  also  differ  if  the  lesion  affects 
l)oth  lateral  halves  of  the  cord  or  only  one. 

Wherever  the  lesion  be  situated  within  the  cervical  enlarge- 
ment, the  arms  and  legs  will  gradually  become  paralyzed ;  the 
arms  and  hands  usually  becoming  first  numb  and  paretic,  and 
the  lower  limbs  exhibiting,  for  some  time,  only  a  sense  of 
weakness  and  evidences  of  an  increased  reflex  excitability.  A 
sense  of  constriction  around  the  chest  (the  so-called  '' cinc- 
ture feeling")  is  generally  present,  the  seat  of  which  varies 
with  that  of  the  exciting  lesion. 

When  the  lesion  is  situated  at  the  upper  part  of  the  en- 
largement, the  motor  and  sensory  symptoms  will  be  manifest- 
ed in  the  lower  extremities,  the  trunk,  and  in  nearly  all  the 

\  The  reader  is  referred  to  the  pages  on  the  third  cranial  and  pneumogastric  nerves 
1  details  as  to  the  effects  upon  the  eye  or  heart. 


344  THE  SPINAL   CORD. 

regions  of  the  upper  extremities.  The  constricting  band  around 
the  thorax  is  referred  to  the  level  of  tJce  clavicles^  and  dyspnoea 
is  often  excessive.  If  you  will  look  at  the  diagrammatic  cut, ' 
you  will  perceive  that  the  brachial  plexus  is  marked  as  asso- 
ciated with  the  upper  part  of  the  cervical  enlargement,  and 
the  ulnar  nerve  with  the  lower  part ;  hence  the  paralysis  of 
the  arms  in  this  case  would  naturally  be  manifested  in  almost 
all  of  the  regions  of  the  upper  extremity,  and  also  in  those 
parts  supplied  by  the  brachial  plexus  above  the  clavicle. 

If  the  lesion  be  situated  in  the  lower  part  of  the  cervical 
enlargement,  the  symptoms  exhibited  will  include  a  loss  of 
faradic  reaction  of  those  muscles  which  are  supplied  by  th^^ 
ulnar  nerve  (rather  than  those  of  the  arm  and  the  extensors 
of  the  forearm),  and  atrophy  of  these  muscles  will  often  be 
developed,  chiefly  in  the  flexors  of  the  wrist  and  the  small 
muscles  of  the  hand."  The  same  sense  of  constriction  (cinc- 
ture feeling),  as  experienced  in  most  spinal  lesions  of  a  local 
character,  will  exist,  but  it  will  be  referred  to  the  upper  part 
of  the  chest.  A  paralytic  condition  of  the  muscles  of  the 
trunk  (the  intercostals,  triangularis  sterni,  and  the  accessory 
muscles  of  respiration),  as  well  as  of  the  abdominal  muscles, 
will  be  detected  in  severe  cases,  rendering  both  inspiration 
and  expiration  embarrassed,  and  thus  adding  to  the  danger 
to  life.  The  lower  limbs  may  exhibit  evidences  of  numbness, 
anaesthesia,  paresis,  or  complete  paralysis,  depending  upon 
the  extent  of  the  lesion  and  the  destruction  done  to  the  tis- 
sues of  the  cord.  A  condition  of  paralysis  may  also  exist  in 
the  upper  extremity. 

In  surgical  injuries  to  the  upper  portion  of  the  cord,  a 
peculiarity  is  often  noticed  in  the  temperature  of  the  body, 
which  is  sometimes  greatly  elevated.  This  clinical  feature 
may  be  associated  with  a  marked  retardation  of  the  action  ol 
the  heart  (apparently  confirming  the  situation  of  an  accelera- 
tory  center  for  that  organ  in  the  spinal  cord). 

'  See  page  340  of  this  volume. 

'  The  reader  is  referred  to  subsequent  pages  for  the  symptoms  of  ulnar  paralysis. 


FOCAL   LESIONS  IN  THE  DORSAL  REGION.  345 

FOCAL    LESIONS    OF   THE    MID-DORSAL    REGION    OF   THE    SPINAL    CORD. 

In  the  early  stages  of  this  condition  the  lower  limbs  be- 
come paretic,  and  a  condition  of  increased  reflex  excitability 
is  manifested  by  a  rigidity  and  stiffness  of  the  impaired  mus- 
cles whenever  the  patient  attempts  to  stand  or  walk.  As  the 
disease  progresses,  the  muscles  become  paralyzed  and  contrac- 
tnred '  (probably  on  account  of  changes  of  a  secondary  char- 
acter in  the  lateral  columns  of  the  cord).  In  some  cases,  the 
reflex  movements  assume  the  type  of  spasms,  so  as  to  exhibit 
both  tonic  and  clonic  contractions.  It  was  this  symptom 
which  suggested  to  Brown- Sequard  the  name  of  "-  spinal  epi- 
lepsy," since  it  occurs  when  the  patient  is  exposed  to  the 
slightest  peripheral  irritation,  and  often  when  in  the  recum- 
bent posture.^  The  sense  of  constriction  around  the  body  is 
referred  to  the  region  of  the  navel,  or  that  of  the  lower  ribs, 
or  possibly  as  high  as  the  axilla,  since  it  may  be  taken  as  a 
relative  guide  to  the  highest  limit  of  the  lesion.  A  peculiarity 
exists  in  this  condition  as  regards  the  bladder  and  the  rec- 
tum ;  although  they  may  be  paralyzed,  they  are  often  enabled 
by  the  aid  of  reflex  action  to  expel  their  contents,  thus  appar- 
ently having  regained  their  function.  In  the  early  stages,  the 
urine  and  fseces  may  be  too  hastily  expelled  for  the  comfort 
of  the  patient,  often  compelling  the  performance  of  either  act 
before  a  proper  place  can  be  reached ;  but,  in  the  advanced 
stages,  the  urine  is  retained  to  such  an  extent  as  to  cause  an 
"overflow,"  which  is  often  mistaken  for  an  actual  inconti- 
nence,' since  a  constant  dribbling  is  present.  This  symptom 
is  always  an  indication  for  the  regular  use  of  a  catheter.  The 
sexual  function  seems  to  be  often  unimpaired,  as  coition  is 
frequently  possible.  It  is  seldom  that  the  paralyzed  muscles 
('xhibit  a  tendency  to  atrophy,  and  the  electrical  reaction  of 

^  A  term  used  in  contradistinction  to  the  word  "contracted,"  to  designate  a  perma- 
nent  shortening  rather  than  a  temporary  response  to  a  motor  impulse. 

^  The  presence  of  urine  in  the  bladder  or  of  faeces  in  the  rectum  may  often  create 
these  spasms. 

^  For  the  diagnosis  between  these  two  conditions,  the  reader  is  referred  to  "  A  Prac- 
Tical  Treatise  on  Surgical  Diagnosis,"  by  the  author.  William  Wood  &  Co.,  New  York, 
1S80. 


346  TEE  SPINAL   CORD. 

the  affected  parts  is  either  normal  or  exaggerated.  The  chief 
seat  of  weakness  is  usually  detected  first  in  the  feet,  and  the 
paralysis  gradually  involves  the  entire  lower  limbs. 

FOCAL  LESIONS  ABOVE  THE   LUMBAR    ENLARGEMENT   OF    THE   SPINAL 

CORD. 

In  this  situation,  a  focal  lesion  of  the  cord  produces  about 
the  same  sensory  and  motor  symptoms  as  those  described  in 
connection  with  a  lesion  of  the  mid-dorsal  region,  with  the 
exception  that  the  reflex  spasms^  present  in  the  paralyzed 
muscles,  are  perhaps  somewhat  less  violent  than  when  the 
lesion  is  higher  up  the  cord.  These  tonic  and  clonic  spasms 
are,  however,  sufficiently  well  marked  to  constitute  a  promi- 
nent symptom,*  and  they  indicate  an  increased  reflex  excita- 
bility of  the  gray  matter  of  the  cord  below  the  seat  of  the 
lesion.  An  ingenious  explanation  of  this  increased  reflex  has 
been  advanced  by  Professor  Seguin  of  this  city,  which  seems 
to  merit  respectful  consideration.  I  quote  from  a  late  paper* 
of  his  upon  affections  of  the  spinal  cord,  as  follows : 

"The  classic  theory  of  the  physiology  of  contracture  in 
hemiplegia  is  that  it  is  due  to  the  secondary  degeneration — 
i,  e.y  actively  caused  by  the  lesion  of  the  posterolateral  col- 
umn. Seven  years  ago  (see  ''Archives  of  Scientific  and  Prac- 
tical Medicine,"  vol.  i,  p.  106,  1873)  I  rejected  this  hypothesis, 
and  suggested  a  different  one,  which  I  have  since  elaborated 
and  taught  in  my  clinical  lectures  at  the  College  of  Physicians 
and  Surgeons,  New  York.  This  hypothesis,  which  I  intend 
shortly  to  publish  in  detail,  is  briefly  that  the  spasm  is  due, 
not  to  direct  irritation  from  the  sclerosed  (?)  tissue  in  the 
postero-lateral  column,  but  to  the  cutting  off  of  the  cerebral 
influence  by  the  primary  lesion,  and  the  consequent  prepon- 
derance of  the  proper  or  automatic  spinal  action — an  action 
which  is  mainly  reflex.  This  theory  explains  the  phenomena 
observed  in  cases  of  primary  spinal  diseases  with  descending 
degeneration,  and  can  be  reconciled  with  results  of  experi- 

'  These  reflex  spasms  have  been  called  by  Brown-S6quard  "  spinal  epilepsy," 
*  "  Annals  of  Anatomical  and  Surgical  Society,"  Brooklyn,  December,  1880. 


FOCAL  LESIONS   OF  THE  LUMBAR  REGION.  347 

ments  on  animals  (increased  reflex  power  of  spinal  cord  after 
a  section  high  up,  Brown- Sequard  ;  inhibitory  power  of  the 
encephalon  on  the  spinal  cord,  Setchenow)." 

The  urinary  and  rectal  organs  are  affected  in  about  the 
same  way  as  in  lesions  of  the  dorsal  region.  Coition  is  often 
possible,  and  erections  are  normally  frequent.  The  rectum  is 
paralyzed,  as  a  rule,  and  constipation  is  usually  present  on 
that  account.  Micturition  becomes  slow  and  interrupted,  as 
the  bladder  grows  paretic,  and  retention  and  overflow  are 
produced  later  on  in  the  disease. 

The  paralysis  of  the  extremities  is  first  noticed  in  the  feet, 
which  have  long  before  exhibited  a  sense  of  weakness  and  easy 
fatigue.  Numbness  and  anaesthesia  usually  accompany  the 
motor  paralysis,  and  extend  as  high  as  the  groin  or  the  waist. 
The  sense  of  a  constricting  band  around  the  body  is  present 
here,  as  in  lesions  of  other  localities,  and  is  referred  to  the  waist, 
below  the  level  of  the  umbilicus,  or  at  the  level  of  the  hips. 

FOCAL   LESIOJ^S   OF  THE   LUMBAR   ENLARGE3IENT. 

If  you  will  look  at  the  diagram  of  the  spinal  cord  upon 
the  blackboard, '  you  will  perceive  that  the  lower  portion  of 
the  lumbar  enlargement  is  represented  as  giving  origin  to  the 
sciatic  nerve ;  hence,  it  is  reasonable  to  expect  that  a  lesion 
situated  in  the  lower  part  of  this  enlargement  would  be  mani- 
fested by  symptoms  of  an  incomplete  paraplegia,  in  which 
the  muscles  supplied  by  the  sciatic  nerves  would  be  the  most 
affected.'  Now,  this  fact  seems  to  be  confirmed  by  clinical 
experience,  since  the  feet,  legs,  posterior  aspect  of  the  thighs, 
and  the  region  of  the  nates  are  chiefly  paralyzed  when  the  le- 
sion is  so  situated.  The  bladder  is  unaffected,  but  the  sphinc- 
ter ani  muscle  is  often  rendered  paretic,  or  it  may  be  entirely 
paralyzed.  The  portions  of  the  limbs  which  are  to  become  the 
seat  of  paralysis  usually  exhibit  a  sense  of  numbness  before 
the  effects  of  the  lesion  are  fully  developed,  and,  in  case  the 

^  The  reader  is  referred  to  the  figure  on  page  340  of  this  volume. 
"^  The  reader  is  referred  to  the  pages  which  treat  of  the  clinical  points  pertaining  to 
the  sciatic  nerve,  for  the  symptoms  of  this  type  of  paralysis. 


348  THE  SPINAL   CORD. 

posterior  columns  of  the  cord  be  involved,  complete  anaesthe- 
sia may  also  exist  in  the  parts  supplied  with  motor  power  by 
the  sciatic  nerve.  The  condition  of  the  paralyzed  muscles, 
as  to  their  electrical  reactions,  and  the  presence  or  absence  of 
the  evidences  of  increased  reflex  excitability  will  depend 
greatly  upon  how  much  damage  has  been  done  to  the  gray 
matter  of  the  lumbar  enlargement.  If  the  gray  matter  be  so 
destroyed  as  to  impair  its  function,  the  reflex  movements  will 
be  absent ;  and,  if  the  trophic  function  of  the  cord  be  afl'ected 
by  changes  in  the  ganglion  cells  of  the  gray  matter,  the  para- 
lyzed muscles  will  undergo  atrophy.  The  sense  of  constric- 
tion, or  ''band  feeling,"  will  usually  be  referred,  in  this  le- 
sion* either  to  the  ankle,  leg,  or  thigh. 

FOCAL    LESIONS    CONFINED    TO    THE    LATERAL    HALF   OF  THE   SPINAL 

CORD. 

In  discussing  the  focal  lesions  of  the  cord,  we  have  de- 
scribed the  clinical  points  which  are  afforded  by  destruction, 
to  a  greater  or  less  extent,  of  the  substance  of  the  cord  in  both 
of  its  lateral  halves  ;  hence,  the  motor  and  sensory  symptoms 
have  been  usually  referred  to  both  sides  of  the  body.  It  was 
necessary  to  thus  describe  them,  since  focal  lesions,  unless 
traumatic,  are  seldom  confined  to  one  lateral  half  of  the 
cord  ;  but,  in  some  cases  which  may  be  presented  to  your 
notice,  where  a  tumor,  a  fractured  vertebra,  a  haemorrhage, 
a  severe  contusion,  or  some  other  localized  lesion  exists,  the 
injury  done  to  the  spinal  cord  may  be  confined  exclusively 
to  one  lateral  half,  resulting  in  one  of  two  named  conditions, 
viz.,  "spinal  hemiplegia"  and  "hemi-paraplegia."  Before 
proceeding  to  the  special  consideration  of  either  of  these 
conditions,  it  may  prove  of  advantage  to  review  some  few 
points  in  the  physiology  of  the  cord,  and  to  again  direct  your 
attention  to  the  two  plates  upon  the  blackboard,  which  are 
already  familiar  to  you. 

This  plate '  shows  you  that  any  lesion  of  a  lateral  Jtalf  of 
the  spinal  cord  must  produce  anaesthesia  in  the  opposite  side 
of  the  body,  since  all  the  sensory  nerves  decussate  and  enter 

'  See  Fijr.  120  of  this  volume. 


FOCAL  LESION   OF  A   LATERAL  HALF  OF  THE  CORD.   349 


the  gray  matter  of  the  cord,  which  serves  as  a  condiictino- 
medium  for  sensory  impressions,  while  the  motor  symptoms 
produced  by  the  same  lesion  must  be  confined  to  the  same 
Hide  of  the  body  as  the  lesion^  since  no  decussation  probably 
occurs  in  the  spinal  cord  (these  fibers  decussating  only  in  the 
medulla  oblongata). 


This    second    diagram'   will  further 


MS      S  M 


:\- 


^t 


assist  you  to  appreciate  the  fact  that 
lateral  lesions,  as  well  as  those  which 
aifect  the  entire  cord,  are  modified,  as 
regards  their  symptomatology,  by  the 
height  of  the  lesion  in  the  cord  ;  since 
the  motor  nerves,  and  the  special  cen- 
ters which  are  situated  in  the  cord  itself, 
will  only  be  affected  when  they  lie  below 
the  seat  of  the  lesion  or  are  directly  in- 
volved in  the  destructive  process.  It 
wil],  therefore,  be  unnecessary  to  enter 
again  into  detail  as  to  the  full  bearings 
of  the  plate,  since  they  are  probably 
fresh  in  your  memory. 

When  the  focal  lesion  is  placed  high 
:ip  in  the  substance  of  the  spinal  cord,  the 
motor  paralysis  affects  one  side  only  of 
the  body  (provided  the  lesion  is  confined  to  a  lateral  half),  and 
the  term  "  spinal  hemiplegia  "  is  applied  to  this  form  of  paral- 
ysis in  contradistinction  to  a  hemiplegia  of  cerebral  origin.  If 
the  spinal  lesion  be  situated  in  the  dorsal  region  and  be  con- 
fined to  the  lateral  half  of  the  cord,  a  motor  paralysis  of  one 
half  of  the  same  side  of  the  body  below  the  seat  of  the  lesion 
is  developed,  a  condition  to  which  the  term  "  hemi-paraple- 
gia "  is  commonly  applied.  In  closing  the  clinical  aspects  of 
lesions  of  the  spinal  cord,  it  will  be  necessary,  therefore,  for 
us  to  consider  the  essential  features  of  these  two  remaining 
conditions. 


\M 


Fig.  127. — A  diagram  to 
show  the  course  of  the 
motor  and  sensory  paths 
in  the  spinal  cord. 
(Brown-Sequard.) 

D,  decussation  of  pyramids ; 
M,  motor  paths  ;  S,  sen- 
sory paths. 


'  The  reader  is  referred  to  page  307  of  this  vohime  for  details  as  to  the  utility  of  this 
figure  in  the  study  of  spinal  affections. 


350 


THE  SPINAL   CORD. 


SPINAL   HEMIPLEGIA. 

In  order  to  produce  a  typical  case  of  this  condition,  it  is 
necessary  to  have  a  lateral  focal  lesion  of  the  cord  in  its  upper- 
most part  (in  or  above  the  cervical  enlargement  of  the  cord).  If 
we  suppose,  then,  that  such  a  lesion  be  present,  let  us  see  what 
we  might  reasonably  expect,  on  purely  physiological  grounds, 
would  be  the  result.     AVe  can  then  examine  the  clinical  rec- 


Medulla. 


Axis.  <^ 

dC.  V.  < 

I    ^  6th  C.  V.  / 

^1    J  Tth  C  V.  <( 

2d  D.  V.  <^ 


11th  D.  V.  <[ 
12th  D.  V.  <^ 

1  L.  v.  <^ 

2  L.  V.  <^ 


Hypo-glossal  N. 

rncumogastric  N. 
Phrenic  N. 

Brachial  plexus. 
Ulnar  nerve. 


Crural  N. 


Sciatic  N. 


Fig.  128. — A  diagram  to  show  the  relation  of  the  spinous  p'occsscs  of  the  veriebrce  to  spi- 
nal nerves.     (Malgaigne  '  and  Seguin.) 

ords  of  such  cases,  and  either  confirm  our  deductions  or  gain 
some  additional  information.  Such  a  lesion  would,  in  the  first 
place,  shut  off  all  motor  impulses  sent  out  from  the  brain  to 
parts  below  the  lesion,  on  the  same  side  as  the  lesion,  since 

'  "  Trait6  d' Anatomic  Chirnrgicale." 


i 


SPINAL  HEMIPLEGIA.  35X 

the  decussation  of  the  motor  fibers  has  already  taken  place  in 
the  medulla  ;  hence  motor  paralysis  should,  theoretically,  oc- 
cur in  the  arm  and  leg  of  the  side  of  the  body  corresponding 
to  the  seat  of  the  exciting  lesion,  and  the  trunk  should  also  be 
i)aralyzed  upon  that  side.  This  we  find,  clinically,  to  be  true,' 
with  the  exception  that  the  intercostal  nerves  often  retain 
their  motor  power  when  the  nerves  of  the  arm  and  leg  are  no 
longer  capable  of  carrying  motor  impulses.  In  the  second 
place,  we  should  expect  to  find  that  the  sensation  of  the  side 
of  the  body  opposite  to  the  seat  of  the  lesion  would  be  de- 
stroyed or  greatly  impaired,  since  the  sensory  nerves  decus- 
sate throughout  the  entire  length  of  the  cord.  This  we  also  find 
confirmed  by  clinical  facts  ;  and  so  perfect  is  this  ansesthesia 
that  the  line  can  often  be  traced  to  the  mesial  line  of  the  body 
exactly,  and  upward  to  the  limit  of  the  exciting  lesion.  In 
the  third  place,  the  situation  of  the  cilio-spinal  center  in  the 
cervical  region  of  the  cord  would  naturally  suggest  some  effects 
ux)on  the  pupil,'  and  the  circulation  and  temperature  of  the 
face,  neck,  and  ear  of  the  same  side.  This  is  also  confirmed,  as 
the  pupil  does  not  respond  to  light,  but  it  still  acts  in  the  ac- 
commodation of  vision  for  near  objects,  and  the  skin  of  the 
regions  named  becomes  red  and  raised  in  temperature.  Fi- 
nally, the  presence  of  "caso-motor  centers  in  the  cord  might 
occasion  a  rise  in  temperature  in  the  paralyzed  muscles  ;  and, 
strangely  confirmatory  of  this  fact,  we  often  find  the  tempera- 
ture of  the  paralyzed  side  of  the  body  hotter  than  that  of  the 
anaesthetic  side. 

In  some  exceptional  cases,  the  face,  arm,  and  trunk  are 
alone  paralyzed,  the  legs  seeming  to  escape,  and  often  giving 
evidence  of  reflex  spasm  (perhaps  most  commonly  on  the 
ansesthetic  side).  This  must  be  explained  as  the  result  of 
incomplete  destruction  of  the  lateral  half  of  the  cord. 

^ThG  researches  of  Brown-Sequard,  as  early  as  1849,  and  his  published  memoirs 
(1863-'5  and  1868,  18G9),  have  probably  done  more  to  clear  up  this  field  and  to  place  it 
upon  a  positive  foundation  than  those  of  any  other  observer. 

2  The  reader  is  referred  to  pages  114  and  135  of  this  volume. 


352  THE  SPINAL   CORD. 

HEMI-PARAPLEGI  A. 

This  condition  is  the  result  of  some  focal  lesion  of  the 
spinal  cord  in  the  dorsal  region,  which  involves  only  its  lateral 
half.  The  results  of  such  a  lesion  differ  but  little  from  those 
of  one  causing  spinal  hemiplegia,  as  regards  the  motor  and 
sensory  symptoms,  excepting  that  the  situation  of  the  excit- 
ing cause  is  below  the  cervical  enlargement,  where  the  nerves 
to  the  upper  extremity  are  given  off,  and  where  the  cilio- 
spinal  center  is  situated.  For  that  reason  the  muscles  of  the 
upper  extremity  are  not  paralyzed,  nor  are  the  effects  upon 
the  pupil  and  the  skin  of  the  face,  ear,  and  neck  (mentioned 
as  present  in  spinal  hemiplegia)  produced.  The  muscles  be- 
low the  seat  of  the  lesion  are  paralyzed  on  the  side  of  the  body 
corresponding  to  the  exciting  cause,  and  the  skin  is  sometimes 
rendered  hypersesthesic  upon  that  side ;  *  while  the  integu- 
ment of  the  side  opposite  to  the  lesion  is  deprived  of  sensi- 
bility. The  bladder  and  rectum  may  be  paralyzed  in  some 
instances.  The  sense  of  constriction,  or  ''band  feeling,"  will 
vary  with  the  seat  of  disease  in  the  spinal  cord.  The  aipount 
of  reflex  irritdbility  and  the  presence  or  absence  of  muscular 
atrophy  in  the  parts  paralyzed  will  depend  upon  the  depth 
of  the  lesion  in  the  spinal  cord  and  the  changes  which  have 
been  produced  in  the  gray  matter.  The  same  increase  of  tem- 
perature in  the  paralyzed  limb,  which  was  mentioned  as  oc- 
curring in  spinal  hemiplegia,  may  also  be  present  in  this  vari- 
ety of  paralysis. 

Should  the  side  affected  with  anaesthesia  give  any  evidence 
of  motor  paralysis  or  muscular  weakness,  or  symptoms  of 
anaesthesia  appear  upon  the  side  where  the  motor  paralysis 
is  present,  you  may  regard  either  one  as  conclusive  evidence 
that  the  exciting  lesion  is  progressing,  and  that  the  opposite 
lateral  half  of  the  cord  is  being  involved  to  a  greater  or  less 
extent. 

'  This  is  probably  due  to  some  irritation  of  the  gi*ay  matter  of  the  cord. 


♦  THE  SPmAL  SERVES. 

THEIR    ORIGIN,   DISTRIBUTION,   FUNCTIONS,   AND 
CLINICAL  IMPORTANCE. 


THE    SPIISrAL   I^EEYES. 


We  have  now  considered  the  general  points  in  the  con- 
struction of  the  cerebro-spinal  axis,  and  the  clinical  facts 
which  pertain  to  the  brain  and  spinal  cord.  We  have  also 
separately  discussed  those  nerves  which  are  connected  with 
the  brain,  and  have  noted  all  the  peculiarities  in  their  distri- 
bution and  anastomoses,  which  seem  to  shed  a  light  upon 
their  physiological  action  or  the  clinical  features  which  each 
of  them  presents.  It  now  remains  for  us  to  investigate  those 
nerves  of  the  neck,  trunk,  and  the  extremities  which  are  con- 
nected with  the  spinal  cord,  and  are  called  "spinal  nerves," 
in  contradistinction  from  the  nerves  of  cranial  origin,  or 
those  of  the  sympathetic. 

The  spinal  nerves  comprise  thirty-one  pairs,  which  escape 
from  each  side  of  the  spinal  cord  by  two  roots,  called  the 
anterior  or  ''motor  root,"  and  the  posterior  or  "sensory 
root."  These  two  roots  join  with  each  other,  in  every  in- 
stance, to  form  one  nerve,  which  is  named  in  accordance  with 
its  situation  and  the  region  of  the  vertebral  column  from 
which  it  escapes ;  since  the  nerves,  so  formed,  pass  through 
foramina  between  the  pedicles  of  the  vertebrse,  throughout 
the  entire  length  of  the  spinal  column.  Thus  we  have  eight 
pairs  of  cervical  nerves^  escaping  upon  either  side  of  the 
cervical  vertebrae  ;  twelve  pairs  of  dorsal  nerves^  bearing  the 
same  relation  to  the  dorsal  region  of  the  spine  ;  five  pairs  of 
lumbar  nerves  on  each  side ;  five  pairs  of  sacral  nerves^ 


356 


THE  SPINAL  NERVES. 


escaping  from  the  foramina  of  that  bone ;  and  one  pair  of 
coccygeal  nerves. 

As  mentioned  in  the  lectures  upon  the  construction  of  the 
spinal  cord,  the  anterior  roots  of  the  spinal  nerves  <ire  con- 
nected with  the  gray  matter  of  the  anterior  horns  ;  while  the 
posterior  roots  are  connected  with  the  posterior  horns  of  the 


Fig.  129. — Cervical  por- 
tion of  the  spinal  cord. 
(Hirschfcld.) 


Fig.    130. — Dorsal   por-         Fig.  131. — hifei-ior  por- 
tion of  the  spinal  cord.  tion  of  the  spinal   cord, 
(Hirschfeld.)  and      cauda       equina. 
(Hirschfeld.) 

1,  antero-inferior  wall  of  the  fourth  ventricle  ;  2,  superior  peduncle  of  the  cerebellum  ; 
3,  middle  peduncle  of  the  cerebellum  ;  4,  inferior  peduncle  of  the  cerebellum  ;  5,  in- 
ferior portion  of  the  posterior  median  columns  of  the  cord  ;  6,  glosso-pharyngeal 
nerve ;  7,  pneumogastric  ;  8,  spinal  accessory  nerve  ;  9,  9,  9,  9,  dentated  ligament ; 
10, 10,  10,  10,  posterior  roots  of  the  spinal  nerves  ;  11,  11,  11,  11,  postenor  lateral 
groove;  12,  12,  12,  VI,  ganglia  of  the  posterior  roots  of  the  nerves  ;  13,  13,  a»/c7v*or 
roots  of  the  nerves  ;  14,  division  of  the  na'ves  into  two  branches  ;  15,  lower  extremity 
of  the  cord  ;  16,  16,  coccygeal  ligament ;  17, 17,  cauda  equina  ;  I — VIII,  ca-vical  nerves  ; 
I,  II,  III,  IV — XII,  dorsal  nei-ves  ;  I,  II — V,  lumbar  nerves  ;  I — V,  saa-al  7ierves. 

gray  matter.     Like  all  sensory  neves,  the  posterior  roots  have 
a  ganglionic  enlargement^  developed  upon  them,  while  the 

'  The  presence  of  a  ganglion  upon  a  cerebro-spinal  nerve  is  always  an  evidence  of  its 
sensory  character. 


THE  MOTOR  AND  SENSORY  ROOTS.  357 

anterior  roots,  being  motor  in  function,  do  not.  The  roots  of 
the  first  cervical  nerves  are  small,  short,  directed  horizontally, 
and  the  anterior  is  the  larger  of  the  two  ;  those  of  the  remain- 
ing cervical  nerves  become  larger,  longer,  and  more  oblique 
as  you  descend  the  cord,  and  the  posterior  root  is  consider- 
ably larger  than  the  anterior.  In  the  dorsal  region,  the  first 
dorsal  nerve  resembles  the  lower  cervical  nerves  as  "to  the 
actual  and  relative  size  of  its  roots,  but  the  roots  of  the  re- 
maining dorsal  nerves  are  smaller  than  those  of  the  cervical 
region,  and  more  nearly  equal  in  their  relative  size.  The 
roots  of  the  lumbar  and  upper  sacral  nerves  again  increase 
in  size  from  above  downward.  Finally,  the  lower  sacral  and 
the  coccygeal  nerves  show  a  gradual  decrease  in  the  size  of 
their  roots,  the  last  sacral  and  the  coccygeal  nerves  having 
the  smallest  roots  of  any  of  the  spinal  nerves.  As  regards 
the  relative  size  of  the  anterior  and  posterior  roots,  the  lum- 
bar, sacral,  and  coccygeal  nerves  exhibit  but  little  difference. 

The  length  and  inclination  of  the  roots  of  the  spinal  nerves 
increase  from  the  first  to  the  last ;  hence  the  place  of  escape 
of  a  spinal  nerve  does  not  indicate  its  seat  of  origin.  As  the 
spinal  cord  does  not  descend  beyond  the  first  lumbar  verte- 
bra, the  length  of  the  roots  of  the  lumbar,  sacral,  and  coccy- 
geal nerves  increases,  from  nerve  to  nerve,  by  the  thickness 
of  one  vertebra. 

The  trunk  of  each  spinal  nerve,  after  its  escape  from  the 
vertebral  canal,  immediately  divides  into  an  anterior  and  a 
posterior  primary  division. 

In  treating  of  the  spinal  nerves,  I  will  first  direct  your 
attention  to  the  four  upper  cervical  nerves,  since  they  enter 
into  the  formation  of  the  cervical  plexus  ;  then  to  the  remain- 
ing cervical  and  the  first  dorsal  nerves,  since  they  enter  into 
the  formation  of  the  brachial  plexus  ;  and,  later  on,  the 
dorsal,  lumbar,  sacral,  and  coccygeal  nerves  will  be  separately 
considered.  By  this  method  of  subdivision,  which  is  the  one 
usually  followed  by  all  authors  upon  anatomy,  the  nerves  can 
be  more  satisfactorily  traced  from  their  origin  to  their  termi- 
nal distribution  than  if  each  nerve  were  treated  of  separately, 

25 


358  THE  SPINAL  NERVES. 

since  some  enter  into  the  formation  of  plexuses,  and  thus  lose 
their  individuality. 

The  axioms  regarding  the  distribution  of  nerves  to  the 
muscles,  joints,  and  skin,  which  I  quoted  in  the  first  lecture 
of  this  v^inter's  course,  will  be  so  constantly  of  use  in  the 
study  of  the  spinal  nerves  that  they  will  again  bear  repetition. 
The  substance  of  my  remarks  in  that  lecture  was  about  as 
follows : 

It  is  claimed  by  John  Hilton '  that,  if  we  trace  the  distri- 
bution of  the  nerve  filaments  from  any  special  nerve  trunk  to 
the  muscles,  we  shall  find  that  only  those  muscles  are  supplied 
by  each  of  the  individual  nerves  which  are  required  to  render 
complete  the  performance  of  the  functions  for  which  that 
nerve  was  designed  ;  and  that,  if  muscles  were  classified  on  a 
basis  of  their  nerve  supply,  instead  of  in  groups  of  mere  rela- 
tionship as  to  locality,  a  self-evident  physiological  relation 
would  be  shown  which  would  tend  greatly  to  simplify  a 
knowledge  of  the  muscular  system  in  its  practical  bearings, 
and  to  prove  a  design  on  the  part  of  the  Creator. 

Thus,  he  says,  we  frequently  find  muscles  close  together 
and  still  supplied  by  separate  nerves,  one  of  which  has  possi- 
bly to  go  a  long  way  out  of  a  direct  course  to  reach  it,  which 
is  contrary  to  the  usual  method  of  ^Nature,  who  always  uses 
the  simplest  means  to  accomplish  her  designs ;  but,  if  we  ex- 
amine the  action  of  these  two  muscles,  we  will  find  that  each 
one  acts  in  unison  with  the  other  muscles  supplied  by  the 
same  nerve,  and  that,  to  produce  this  perfect  accord,  ISTature 
takes  what,  to  a  hasty  glance,  would  seem  to  be  a  needless 
step. 

He  also  lays  down  certain  axioms,  pertaining  to  the  dis- 
tribution of  nerves  and  the  diagnostic  value  of  pain,  which 
have  been  often  repeated  in  these  lectures,  and  can  not  but  be 
most  profitable  to  those  who  use  them  as  a  guide.  They  are 
as  follows : 

"Superficial  pains  on  'both  sides  of  the  body,  ichicli  are 
symmetrical^  imply  an  origin  or  cause^  the  seat  of  which  is 

1  "  Rest  and  Pain,"  London,  1876  (New  York,  1879j. 


THE  AXIOMS   OF  NERVE  DISTRIBUTION-.  359 

central  or  h  Hater  at ;  while  unilateral  pain  implies  a  seat  of 
origin^  which  is  one-sided^  and^  as  a  rule,  exists  on  the  same 
side  of  the  body  as  the  pain ^ 

The  bearings  of  this  first  axiom  will  be  rendered  very  ap- 
parent when  the  regions  of  the  neck  and  trunk  are  considered, 
since  the  symptom  of  local  pain  is  of  the  greatest  value  in 
connection  with  diseases  affecting  the  bones  of  the  spinal  col- 
umn and  the  spinal  cord  which  they  invest ;  but  that  the 
same  rule  may  be  applied  to  any  of  the  cranial  nerves,  with  a 
degree  of  certainty  which  seldom  admits  of  error,  has  been 
shown  in  cases  quoted  in  connection  with  the  motor  oculi, 
trigeminus,  facial,  and  other  nerves. 

The  second  axiom  is  as  follows : 

''  The  same  trunks  of  nerves,  whose  branches  supply  the 
groups  of  muscles  moving  a  joint,  furnish  also  a  distribu- 
tion of  nerves  to  the  skin  over  the  insertions  of  the  same  mus- 
cles ;  and  the  interior  of  the  joint  moved  by  these  muscles 
receives  a  nerve  supply  from  the  same  source^ 

By  this  axiom,  a  physiological  harmony  is  shown  between 
these  various  cooperating  structures.  Thus,  any  joint,  when 
inflamed,  may,  by  a  reflex  act  through  motor  branches  from 
the  same  trunk  by  which  it  is  itself  supplied,  control  the  mus- 
cles which  move  it,  and  thus  insure  the  rest  and  quiet  neces- 
sary to  its  own  repair. 

Spots  of  local  tenderness  in  the  cutaneous  surface  may, 
for  this  reason,  likewise  be  often  considered  as  a  guide  to  a 
source  of  irritation  of  some  of  the  structures  supplied  by  the 
same  nerve,  viz.,  the  muscles  underneath  it,  or  the  joints 
which  are  moved  by  them  ;  and,  thus,  even  remote  affections 
can  be  accurately  determined,  which,  were  this  axiom  not 
used  as  a  guide,  might  escape  recognition  till  an  advanced 
stage  of  the  disease  had  been  reached. 

It  is  well,  however,  to  quote  one  other  axiom,  laid  down 
by  the  same  author,  before  leaving  the  subject  of  the  diag- 
nostic value  of  the  cutaneous  nerves  as  indicators  of  existing 
disease  of  other  organs,  viz.  : 

'-^  Every  fascia  of  the  body  has  a  muscle  or  muscles  at- 


860  TEE  SPINAL  NERVES. 

lacked  to  it ;  and  every  fascia  must  he  considered  as  one  of 
the  points  of  insertion  of  the  muscles  connected  to  it^^^  in  fol- 
lowing the  previous  axiom  as  to  the  cutaneous  distribution 
of  nerves. 

This  guide  is  especially  important  in  case  the  rule  be  ap- 
plied to  the  extremities  (arms  and  legs)  where  these  fascice 
extend  over  large  surfaces,  more  or  less  remote  from,  and  ap- 
parently unconnected  with,  the  muscles  attached  to  them  ;  but 
it  is  mentioned  in  this  connection  for  the  especial  object  of 
calling  the  attention  of  the  reader  to  those  general  rules  which 
govern  the  distribution  of  the  nerves  in  their  entirety,  before 
proceeding  to  apply  them  in  all  their  individual  bearings  : 

Without  this  nervous  association  between  the  muscular 
structures  and  those  composing  the  joints,  there  could  be  no 
intimation  given  by  the  internal  parts  of  their  exhaustion  or 
fatigue.  Again,  through  the  medium  of  this  same  association 
between  the  skin  and  the  muscles,  great  security  is  given  to 
the  joints,  by  the  muscles  being  made  aware  of  the  point  of 
contact  of  any  extraneous  force  or  violence.  Their  involun- 
tary contraction  instinctively  makes  the  tissues  surrounding 
the  joints  tense  and  rigid,  and  this  brings  about  an  improved 
defense  for  the  subjacent  joint  structures. 

From  the  conclusion  of  his  great  work,  in  which  Hilton  en- 
deavors to  prove  that  mechanical  rest  may  be  used  as  a  cure 
for  most  of  the  surgical  disorders,  the  following  sentences  are 
quoted,  since  they  can  not  be  too  often  repeated  : 

''  I  have  endeavored  to  impress  upon  you  the  fact  that 
every  pain  has  its  distinct  and  pregnant  signification  if  we 
icill  hut  carefully  search  for  it. 

"In  the  pain  which  follows  the  intrusion  of  a  particle  of 
dust  on  to  the  conjunctiva,  and  the  closure  of  the  eyelid  for 
the  security  of  rest,  up  to  the  most  formidable  diseases  which 
we  have  to  treat — pain  the  monitor,  and  rest  the  cure — are 
starting  points  for  contemplation,  which  should  ever  be  pres- 
ent to  the  mind  of  the  surgeon." 

Now,  if  you  will  thoroughly  grasp  these  axioms,  not  only 
as  mere  words,  but  as  grand  principles^  which  can  be  used 


PROPER   USE  OF  TABLES  OF  NERVES.  361 

by  you  in  your  e very-day  experience  as  counselors  of  the 
sick,  you  will  be  better  able  to  appreciate  tlie  tables  of 
nerve  distribution  which  I  am  constantly  presenting  to  you 
upon  the  blackboard,  so  that  you  can  record  them  in  your 
note-books.  These  tables  enable  you,  at  a  glance,  to  see  to 
what  muscles  each  separate  nerve  sends  filaments  of  distribu- 
tion, and  thus  innumerable  problems  are  being  constantly 
suggested  to  you  of  this  character  :  Why  does  this  nerve  sup- 
ply the  muscles  mentioned  and  omit  those  in  the  immediate 
vicinity  \  What  is  the  common  physiological  function  which 
these  muscles  are  destined  to  perform  \  How  may  this  nerve 
be  classed  from  its  physiological  action  \ 

It  is  only  by  such  a  system  of  self -inquiry  and  self-examina- 
tion that  you  are  enabled  to  become  the  master  of  the  science. 
The  nerves  are  then  no  longer  mere  cords,  running  without  a 
plan,  and  serving  only  as  a  tax  upon  the  memory,  but  electric 
wires,  placed  with  a  system  which  we,  as  yet,  can  not  begin 
to  understand  in  its  wonderful  adaptability  to  the  demands  of 
the  body,  but  which  a  little  study  will  show  is  remarkable  for 
its  simplicity  of  distribution,  if  we  but  seek  for  the  function 
of  each  nerve.  To  a  student  of  this  character,  the  nerves  be- 
come a  source  of  never-ending  delight,  since  they  serve  as  the 
key  to  many  problems  in  anatomy  which  had  previously  been 
involved  in  obscurity.  We  thus  learn  the  action  of  the  mus- 
cles^ since  the  nerves  which  supply  any  special  group  enable 
you  at  once  to  tell  that  those  have  a  similarity  of  function 
which  are  supplied  from  the  same  source,  while  those  sup- 
plied from  different  sources  are  not  only  dissimilar  in  their 
action,  but  have  some  bond  of  sympathy  with  other  muscles 
(possibly  far  distant)  which  are  similarly  supplied.  I  believe 
that  the  day  is  not  far  off  when  the  nervous  supply  v^^tM  consti- 
tute the  universally  recognized  basis  upon  which  muscles  will 
be  divided  into  groups  ;  and,  when  that  day  comes,  the  labor 
of  the  student  will  be  greatly  lessened,  and  his  grasp  of  the  sub- 
ject be  of  a  higher  and  more  comprehensive  order.  We  will  now 
pass  to  the  consideration  of  the  upper  four  cervical  nerves,  and 
the  cervical  j)lexus  which  is  formed  by  their  anterior  branches. 


362 


THE   SPINAL  NERVES. 


THE  UPPER  CERVICAL  NERVES. 


A  CHART  OF  THE  KERVES  OF  THE  CERVICAL  REGION^. 


First    Cervical 
Nerve 
{Suh-occipital). 


Posterior  division. 


Anterior  division. 


Second  Cervical 
Nerve. 


Posterior    division 
(very    large     in 
size). 


t  Anterior  division. 


Posterior  division. 


Third   Cervical 
Nerve. 


f  Branch  to  posterior  division  of  second  cervical, 
Branches  to  the  posterior  <rramo-verlebral  set  of 

muscles, 
Branch  to  com'plexus  muscles, 
Branch  to  integument  of  occiput. 
Branch  to  rectus  cap.  ant.  major. 
Branch  to  rectus  cap.  ant.  minor, 
Branch  to  rectus  cap.  lateralis. 

r  Second  cervical. 
Communicating    J   Pneumogastiic, 
branches  to  ]   Hypo-glossal, 

[^  Superior  cervical  ganglion. 
Branch  to  occipito-atloid  articulation. 

(  Splenius, 
External  branch  J  Cervicalis  ascendens, 
/         I  •     \  -^  Transversalis  colli, 
(supplymg)  ^1  Trachelo-mastoid, 
(^  Complexus. 

f  Joins   with    first    cervicr.l 
nerve. 
Supplies  integument  of  oc- 
ciput as  far  as  vertex, 
Gives  an  auricular  braruh 
to  skin  of  ear. 
Filament  to  stcmo-mastoid. 
Ascending  branch  (to  first  cervical  nerve). 
Descending  branch  (to  third  cervical  nerve), 
Filament  to  communicans  noni  nerve. 
Small  occipital  nerve  (occipitalis  minor). 

f  Splenius, 
External   branch  j  Cervicalis  ascendens, 
(supplying)    j  Transversalis  colli, 
(^  Trachelo-mastoid. 
Internal    branch   S  t  4  *    ^      •     * 

(supplying)  ]  J^i<^9^^^<^^  of  occiput. 

f  Auricularis  magnuSj 
Superficial  co'vicalj 
Branch  to  second  cervical 


Internal    branch 
( Great  occipital  -l 
nerve). 


Ascending 

branches. 


Fourth    Cervi- 
cal Nerve. 


nerve, 
Branch  to  the  spinal  acces- 
sory. 
.  Anterior  division.   ■{  f  Filament  to  fourth  nerve, 

Filament  to  levator  anguli 
Descending  |      scapuUe, 

branches.  ■{  Supra-clavicular^ 

Filament  to  communicans 
I      noni  nerve, 
[  (^  Filament  to  phrenic  nerve. 

Posterior  division  (distributed  to  muscles  of  the  back). 
(  Filament  to  third  cervical  nerve, 
Filament  to  filth  cervical  nerve, 
Anterior  division.   ■<  Filament  to  jt)/ir<?wic  n^-w, 

1  Filament  to  scalenus  medius, 

[  Filaments  to  supraclavicular  nei've. 


'  Modified  from  a  table  in  the  "Essentials  of  Anatojiiy"  (Darling  and  Ranney). 
York,  Putnam's  Sons,  1880. 


New 


THE  UPPER   CERVICAL  NERVES. 


363 


If  you  will  look  at  the  table,  which  I  have  had  copied  for 
your  inspection, '  you  will  perceive  that  each  of  the  upper  four 
cervical  nerves  gives  off  an  anterior  and  posterior  branch,  im- 
mediately after  their  escape  from  the  vertebral  canal,  and  that 
the  distribution  of  each  of  these  branches  is  shown  in  detail. 
You  will  perceive  that  every  branch  which  supplies  the  in- 


FiG.  132, — Posterior  branch  of  the  second  cervical  nerve.     (Arnold.) 

1,  trunk  of  the  facial;  2,  its  superior  branch,  or  temporo-facial ;  3,  the  inferior  branch, 
or  eervico-facial ;  4,  its  posterior  auricular  branch ;  5,  auriculo-temporal ;  6,  auri- 
cularis  magnus  from  the  cervical  plexus ;  7,  its  mastoid  branch ;  8,  supra-acromial 
branch;  9,  supra-clavicular  branch;  10,  accessory  occipitalis  minor;  \\,  occipitalis 
major ;  12,  frontal  division  of  the  ophthalmic  nerve;  13,  infra-orbital  branch  of 
the  superior  maxillary ;  14,  mental  branches  of  the  inferior  dental  nerve ;  A,  pla- 
tysma  myoides-  B,  sterno-mastoid ;  C,  trapezius. 

tegument  alone  is  underscored,''  while  the  muscular  branches 
are  not.  Thus,  the  great  occipital,  small  occipital,  great  au- 
ricular, superficial  cervical,  and  supra-clavicular  nerves  are 


See  table  on  the  preceding  page. 


■-  Italicized  in  the  table. 


364 


THE  SPINAL  NERVES. 


made  particularly  prominent.  It  will  tend,  however,  to  sim- 
plify the  study  of  this  table,  if  you  will  compare  it  with  the 
one  adjoining,  which  shows  the  construction  of  the  cervical 
plexus. 

This  plexus  is  formed  by  the  anterior  brandies  of  these 
four  nerves,  so  that  you  will  find  the  same  nerves  mentioned 
in  both  tables  ;  since,  in  the  first  table,  a  nerve  may  be  men- 
tioned as  one  of  the  terminal  filaments  of  a  special  trunk, 
while,  in  the  second  table,  it  will  be  enumerated  as  one  of  the 
'branches  of  the  plexus.  I  mention  this  point,  lest  some  con- 
fusion may  arise  in  your  minds  as  to  the  apparent  contradic- 
tion of  statement,  as  well  as  for  the  purpose  of  impressing  upon 
you  the  fact  that  a  branch  of  any  nerve  plexus  can  usually  be 
traced  as  arising  from  some  special  nerve  or  nerves,  which  as- 
sist to  form  that  plexus.  Thus  we  have  the  phrenic  nerve 
arising  by  three  heads  (third,  fourth,  and  fifth  cervical),  and, 
in  part,  a  branch  of  three  nerves ;  and  again,  the  comviuni- 
cans  noni  nerve,  which  goes  to  join  a  branch  of  the  hypo- 
glossal,' arises  by  two  heads  (second  and  third  cervical). 


THE   CERVICAL   PLEXUS   OF   NERVES. 


Anterior     " 

branch  of  Ist 

Cervical 

nerve. 

c 

PI 

Anterior 

w 

branch  of  2d 

-«- 

Cervical 

o 

nerve. 

> 

■  ^- 

Anterior 

"fl 

branch  of  3d 

Cervical 

nerve. 

a 

w 

Anterior 

branch  of  4th 

Cervical 

nerve. 

Sttperficial 
branches 
(integument- 
ary;. 


Ascending 
set, 


Occipitalis  minor Filament  to  attollens  aurem. 

Auricularis  mafjnua. 

Superficlalis  colli Branch  to  platysma. 


Descending 


! 

(  (  Sternal, 

<  Supra-clavicu'ar  bninches.-<  Clavicular, 
(  (  Acromial. 


Deep 

BRANCnES. 


Internal  set. 


I.  External  set. 


1  Pneumosrastric, 
Communicating.'-?  Hypo-glossal, 
/  Sympathetic. 
I  Kect.  cap.  ant.  major. 
Muscular  -^  Kect.  cap.  ant.  minor, 

{  Rect.  cap.  lateralis. 
Comtvvnicans  noni. 
|_  Phrenic. 

{Sterno-mastoid, 
Levator  anguli  scapulae, 
Trapozms, 
Scalenus  med. 

Communicating  with  spinal  accessory  nerve. 


The  table  which  illustrates  the  method  of  construction  of 
the  cervical  plexus  and  its  branches  of  distribution  may  be 

'  See  page  276  of  this  volume. 

2  The  loop  between  the  first  and  second  cervical  nerves  usually  gives  off  the  communi- 
cating branches  to  pneumogastric  and  hypo-glossal  nerves  and  to  the  superior  cervical 
ganglion  of  the  sympathetic,  while  the  third  and  fourth  cervical  nerves  give  communicat 
ing  branches  to  the  main  cord  of  the  sympathetic  nerve. 


I 


THE   CERVICAL  PLEXUS   OF  NERVES. 


365 


studied  with  some  advantage.  It  will  be  seen  tliat  the  plexus 
gives  off  two  distinct  sets  of  branches,  called  the  superficial 
•nd  the  deep,  since  the  former,  as  the  name  indicates,  are  all 


Fig.  133. — Superficial  branches  of  the  cer^vical plexus.     (Hirschfeld.) 

1,  superficialis  colli ;  2,  2,  its  descending  branches ;  3,  its  ascending  branches  ;  4,  filaments 
of  anastomosis  with  the  facial ;  5,  auviculai-is  magnus ;  0,  its  parotid  branch  ;  7,  its 
external  auricular  branch;  8,  upper  part  of  the  same  branch,  crossing  the  fibrous 
tissue  which  surrounds  the  root  of  the  helix,  and  supplying  the  external  surface  of 
the  pinna;  9,  internal  auricular  branch;  1<»,  filament  of  anastomosis  between  this 
branch  and  the  posterior  auricular  of  the  facial ;  11,  occipitalis  minor;  12,  branch  of 
communication  with  the  occipitalis  major ;  13,  accessory  occipitalis  minor ;  14,  branches 
to  the  integument  on  the  back  of  the  neck;  15,  supra-clavicular  branches,  sternal 
portion;  16,  clavicular  portion;  IT,  supra-acromial  branches,  anterior  division;  18, 
posterior  division  ;  19,  branch  to  trapezius  from  cervical  plexus  ;  20,  branch  to  tra- 
pezius from  the  spinal  accessory,  and  anastomosing  with  the  preceding;  21,  branch 
to  the  levator  anguli  scapulae  ;*  22,  trunk  of  the  facial ;  23,  its  posterior  auricular 
branch  ;  24,  its  cervical  and  mental  branches. 


THE  SPINAL  NERVES. 


cutaneous,  while  the  latter  are  distributed  to  muscles  and  ad- 
jacent nerves.  The  superficial  or  integumentary  set  comprises 
four  nerves,  three  of  which  ascend  toward  the  head,  while  the 
remaining  one  descends  toward  the  shoulder  ;  the  deep  set  is 
subdivided  into  branches  which  pass  toward  the  mesial  line  of 
the  trunk,  the  internal  set,  and  those  which  pass  away  from 
the  mesial  line,  the  external  set. 

SUPERFICIAL  BRANCHES   OF  THE   CERVICAL  PLEXUS. 

The  superficial  set  of  branches  is  of  the  greatest  impor- 
tance to  the  physician,  since  the  symptom  of  pain  is  often  a 
most  positive  guide  to  disease,  which  can  be  localized  by  a 
thorough  knowledge  of  the  nerves.     The  sub-occipital  nerve 


Fig.  134.—  The  nerve  supply  of  the  posterior  part  of  the  head.     (Hilton.) 

A,  region  supplied  by  the  great  occipital  nerve  ;  B,  region  supplied  by  the  small  occipital 
nerve ;  C,  region  supplied  by  the  auiiculo-temporal  nerve. 


(first  cervical),  the  great  and  small  occipital  nerv^es  (branches 
of  the  second  cervical),  and  the  auricularis  magnus  (a  branch 
of  the  third  cervical)  are  all  distributed  to  the  integument  of 
the  scalp^  in  the  posterior  region  of  the  head,  covering  the 
space  which  extends  from  the  neck  to  the  vertex  of  the  cra- 
nium.    The  plate  which  I  now  show  you  w^as  designed  by 


SUPERFICIAL  BRANCHES  OF  CERVICAL  PLEXUS.      367 

Hilton,'  to  illustrate  the  results  of  careful  experiment  as  to 
the  limits  of  the  cutaneous  distribution  of  each  of  these 
nerves. 

In  my  lecture  upon  the  distribution  of  the  fifth  cranial 
nerve,  I  called  your  attention  to  the  diagnostic  value  of  the 
cutaneous  distribution  of  the  nerves  of  the  ear.     It  may  be 


Fig.  135, —  The  nerve  supply  of  the  posterior  portioti  of  head  and  neck.     (Modified  from 

Flower.) 

1,  region  supplied  by  the  great  occipital  nerve  ;  2,  region  supplied  by  the  auriculo-tempo- 
ral  nerve  ;  3,  region  supplied  by  the  small  occipital  nerve  ;  4,  region  supplied  by  the 
great  auricular  nerve  ;  5,  region  supplied  by  the  third  cervical  nerve. 

well  to  again  state  that  the  integument  of  the  pinna  is  sup- 
plied by  the  fifth  cranial,  the  great  auricular,  the  auricular 
branch  of  the  great  occipital,  and  the  small  occipital  nerves, ' 
and  to  impress  upon  you  that  the  limits  of  the  distribution  of 
each  are  now  so  well  defined  as  to  afford  a  clew,  in  many 
instances  where  pain  is  confined  to  this  region,  to  the  seat  of 
the  exciting  cause. 

^  Op.  cit. 

^  The  auricular  branch  which  Hilton  lays  stress  upon,  as  supplying  the  lobule  of  the 
I  r  with  sensation,  may  be  given  off  either  by  the  anterior  or  posterior  division  of  the 
eond  cervical  nerve.  In  the  table  of  the  distribution  of  the  cervical  nerves  I  have  put 
it  down  as  a  branch  of  the^rrm^  occipital  nerve,  since  that  is  its  most  common  origin  ;  but 
it,  not  infrequently,  is  found  to  arise  from  the  small  occipital  nerve,  in  which  case  it 
would  be  derived  indirectly  from  the  anterior  division  of  the  second  cervical,  rather  than 
from  the  posterior  division. 


368  THE  SPIXAL  NERVES. 

The  descending  branches  of  the  superficial  set  of  the  cervi- 
cal plexus  (supra-clavicular)  arise  from  the  third  and  fourtli 
cervical  nerves,  and  are  distributed  to  the  integument  cov- 
ering the  lower  portion  of  the  neck  and  the  regions  of  the 
sternum,  clavicle,  and  acromion.  The  fact  that  the  filaments 
of  these  nerves  are  distributed  to  the  fascia  covering  tlu 
upper  portion  of  the  chesty  below  the  clavicle,  is  made  a 
point  of  diagnostic  importance  by  Hilton,  since  cases  of  dis- 
ease of  the  spinal  column,  in  the  region  of  escape  of  the  third 
or  fourth  cervical  nerves,  or  the  existence  of  pressure  along 
the  course  of  these  nerves,  have  been  suggested  to  him  by 
pain  in  this  region,  and  thus  detected  far  away  from  the  seat 
of  pain.  He  says  :  ''As  nothing  but  the  nerves  can  produce 
pain,  this  simple  distribution  ought  to  remind  us  of  the  fact 
that,  if  a  patient  complains  of  pain  in  this  part  of  the  chest, 
the  cause  may  lie  in  one  of  two  directions.  It  may  depend 
upon  disease  of  the  cervical  region  of  the  spine,  or  in  connec- 
tion with  some  disease  affecting  the  origin  of  the  upper  dorsal 
nerves." 

The  cervical  plexus  lies  upon  the  scalenus  medius  and  the 
levator  anguli  scapulae  muscles,  and  is  covered  by  the  sterno- 
mastoid  muscle  ;  hence,  all  of  its  superficial  branches  emerge 
from  beneath  the  posterior  border  of  this  latter  muscle.'  The 
muscles  which  the  plexus  supplies  directly  are  the  three 
which  lie  in  contact  with  it  and  the  trapezius.  ]S'ow,  it  will 
be  remembered  that  the  trapezius  and  the  stemo-mastoid 
muscles  have  another  source  of  nervous  suj^ply,  viz.,  the  spi- 
nal accessory  nerve.'  This  fact  suggests  that  these  muscles 
must  each  belong  to  two  groups  :  the  first,  those  which  con- 
trol pTionation  ; '  the  second,  those  which  insure  the  ordinary 
motions  of  the  neck.  In  the  same  way,  the  platysma  muscle, 
by  its  nervous  supply,  is  clearly  stamped  as  not  only  a  mus- 
cle of  the  neck,  but  also  one  of  expression^*  since  the  facial 
nerve  supplies  it,  as  well  as  the  cervical  plexus. 

^  See  figure  on  page  005  of  this  volume. 

'  See  page  262  of  this  volume. 

'  See  page  263,  previous  lecture,  upon  this  nerve. 

^  For  the  action  of  this  muscle  in  the  expression  of  melancholy,  sec  the  facial  nerve. 


COMMUmCANS  NONI  NERVE,  369 

DEEP   BRANCHES   OF   THE   CERVICAL   PLEXUS. 

A  secoud  reference  to  the  table,  in  which  the  branches  of 
this  plexus  are  shown,  will  enable  you  to  recall  the  subdivis- 
ion of  the  deep  branches.  The  set  that  passes  toward  the 
mesial  line  of  the  body  comprises  the  muscular  filaments  to 
the  recti  muscles,  the  communicating  branches  to  adjacent 
nerves,  and  two  specially  named  trunks,  the  phrenic  and  com- 
municans  noni  nerves  ;  while  the  set  which  passes  toward  the 
periphery  of  the  neck  comprises  the  muscular  branches  to  the 
sterno-mastoid,  trapezius,  levator  anguli  scapulae,  and  the 
scalenus  medius,  and  communicating  filaments  to  adjacent 
nerves. 

The  filaments  of  communication  between  the  cervical 
plexus  and  the  pneumogastric,  hypo-glossal,  spinal  accessory, 
fifth  cranial,  and  sympathetic  nerves,  have  been  already  dis- 
cussed in  connection  with  each  of  these  nerves.  They  all  in- 
dicate some  definite  purpose  on  the  part  of  Nature,  and  can 
best  be  reviewed  by  a  careful  perusal  of  the  notes  taken  by 
you  in  the  early  part  of  this  course  of  lectures. '  Many  of  the 
diagrams  of  the  special  nerves  mentioned  will  make  points 
clear  to  you  which  it  is  useless  to  repeat. 

The  communicans  noni  nerve,  whose  origin  can  be  traced 
to  two  filaments  connected  with  the  second  and  third  cervical 
nerves,  is  of  surgical  interest  from  the  relation  which  it  bears 
to  the  sheath  of  the  carotid  artery  ;  and  the  branches  which 
are  given  off  from  the  loop,  formed  by  its  junction  with  the 
descendens  noni  nerve,  can  be  seen  by  referring  to  the  dia- 
gram of  the  hypo-glossal  nerve."  Occasionally  this  nerve  is 
found  to  enter  the  sheath  of  the  carotid  artery,  and  to  anasto- 
mose with  the  descendens  noni  nerve  in  this  abnormal  situa- 

^  For  the  association  between  the  fifth  cranial  nerve  and  the  second  cervical  in  the  in- 
tegumentary supply  of  the  ear,  see  page  157  ;  between  the  facial  nerve  and  cervical 
nerves,  see  page  186  ;  between  the  pneumogastric  nerve  and  the  arcade  formed  by  the  first 
and  second  cervical  nerves,  see  diagram  of  pneumogastric  on  page  238  ;  between  the 
si)inal  accessory  nerve  and  the  upper  cervical  nerves  and  its  physiological  bearing,  see 
pages  262  and  267 ;  finally,  between  the  hypo-glossal  nerve  and  the  communicans  noni 
nerve,  see  plate  on  page  275  of  this  volume. 

^  See  page  275  of  this  volume. 


370  THE  SPINAL  NERVES. 

tion.'  From  the  loop  which  it  helps  to  form,  filaments  are 
given  to  the  stemo -thyroid,  sterno-hyoid,  and  both  bellies  of 
the  omo-hyoid  muscle.  Thus  these  muscles  are  placed  under 
the  control  of  two  nerves  ;  the  one  (communicans  noni  nerve) 
enabling  them  to  act  in  harmony  with  the  muscles  of  the  neck, 
while  the  other  (descendens  noni  nerve)  enables  them  to  assist 
in  depressing  the  larynx  and  the  hyoid  bone,  after  the  bolus 
of  food  has  passed  the  isthmus  of  the  fauces,  thus  acting  in 
harmony  with  the  tongue,  which  is  also  supplied  by  the  hypo- 
glossal nerve.  We  can  perceive,  therefore,  that  these  mus- 
cles are  concerned  in  two  distinct  functions — the  movements 
of  the  neck  and  the  act  of  deglutition  and  speech ;  hence  they 
must  of  necessity  be  separately  supplied  by  the  nerves  of  the 
neck  and  that  of  the  tongue,  in  order  to  properly  perform  the 
two  acts  independently  of  each  other. 

The  phrenic  nerve,  called  also  the  ''internal  respiratory 
nerve  of  Bell," '  arises,  by  three  heads,  from  the  third,  fourth, 
and  fifth  cervical  nerves.  Its  course  and  distribution  give  it  a 
surgical  as  well  as  a  physiological  importance.  It  lies  in  front 
of  the  scalenus  anticus  muscle,  and  thus  in  relation  to  the 
second  portion  of  the  subclavian  artery ;  lower  in  the  neck, 
it  passes  between  the  subclavian  vein  and  the  first  portion  of 
the  subclavian  artery ;  when  it  has  entered  the  superior  open- 
ing of  the  chest,  its  course  upon  the  left  side  of  the  body  lies 
in  front  of  the  arch  of  the  aorta  and  the  pulmonary  artery, 
but  upon  the  right  side  the  nerve  passes  between  the  superior 
vena  cava  and  the  right  innominate  vein  ;  each  nerve  crosses 
in  front  of  the  root  of  the  corresponding  lung,  gives  off  twigs 
to  the  pericardium  and  pleura,  and  perforates  the  diaphragm, 
to  be  distributed  to  its  under  surface.  Both  nerves  give  fila- 
ments to  the  phrenic  plexus  of  the  sympathetic,  and  the  right 
nerve  furnishes  some  filaments  to  the  diaphragmatic  ganglion. 

The  distribution  of  the  phrenic  nerves  to  the  diaphragm 
is  mentioned  by  Hilton'  as  one  of  the  simple  devices  of 

'  It  is  sometimes  found  beneath  the  jugular  vein,  and,  occasionally,  in  front  of  it. 
^  This  name  was  applied  to  the  phrenic  nerve  by  Bell,  since  it  passes  internally  to  the 
chest  wall,  and  assists  in  the  physiological  act  of  respiration.  ^  Op.  cit. 


THE  PHRENIC  NERVE.  371 

Nature  to  guard  the  nerves  from  injury.  I  quote  from  his 
excellent  treatise  as  follows:  "As  a  rule,  nerves  enter  the 
muscles  where  they  will  be  most  secure  from  pressure,  and  it 
is  curious  to  observe  how  careful  Nature  has  been  in  this  re- 
spect to  guard  one  of  the  most  important  nerves  in  the  body. 
The  phrenic  nerves  (our  life  hangs  on  these  threads),  after 
})assing  through  the  chest,  traverse  the  diaphragm  and  dis- 
tribute their  branches  to  the  under  surface  of  the  diaphragm, 
and  are  so  situated  that  they  can  not  be  compressed  during 
respiration.  If  they  were  situated  upon  the  upper  surface 
of  the  diaphragm,  where  there  is  a  constant  and  forced  con- 
tact between  the  base  of  the  lung  and  the  superior  aspect  of 
the  diaphragm,  and  especially  so  during  a  retained  inspira- 
tion, it  is  obvious  that  the  filaments  of  the  phrenic  nerve 
would,  under  such  circumstances,  be  exposed  or  subjected  to 
compression,  and  the  action  of  the  diaphragm  would  be  dan- 
gerously interfered  with.  The  nerves  are,  however,  distrib- 
uted to  the  under  or  concave  surface  of  the  diaphragm  ;  the 
whole  tendency  of  gTavitation  being  to  remove  the  liver,  the 
stomach,  and  the  spleen  away  from  them,  so  as  to  enable  the 
nerves  to  carry  on  their  influence  to  the  diaphragm  unmo- 
lested." 

How  extraordinary  is  it  that  the  phrenic  nerve  (a  nerve 
so  important  to  life)  can  pass  through  the  chest  between  the 
dilated  heart  and  the  inflated  lungs,  and  yet,  as  far  as  we 
know,  never  receive  any  untoward  influence  from  pressure ! 
It  is  true  that  the  lungs  have  a  remarkably  definite  concave 
form  toward  the  heart,  arching  over  the  course  of  the  phrenic 
nerve  ;  but,  when  the  lungs  are  emphysematous,  it  seems 
quite  probable  that  these  nerves  might  suffer  from  pressure, 
and  cause  some  difficulty  in  breathing.  When  extravasation 
of  air  occurs  from  rupture  of  the  trachea  or  a  large  bronchial 
tube,  the  patient  dies  rapidly  from  extreme  shortness  of 
l)reath ;  and  this  can  be  explained  by  the  fact  that  the  air 
enters  the  tract  of  the  phrenic  nerve,  thus  causing  extreme 
pressure  and  death  from  paralysis  of  the  diaphragm. 

The  distribution  of  the  phrenic  nerves  to  the  pericardium 


372  THE  SPINAL  NERVES. 

seems  to  warrant  the  supposition  of  Hilton  that  the  pericardi- 
um may  be  considered  as  a  portion  of  the  fascial  tendon  of 
the  diaphragm,  since  it  is  closely  identified  with  it,  and  is  acted 
upon  by  it,  at  all  times.  It  may  also  be  considered  as  pro])- 
able  that  the  phrenic  nerves  are  endowed  with  some  sensor  1/ 
filaments,*  by  communication  with  other  nerves  ;  and  the 
analogy  of  the  pericardium  and  diaphragm  to  a  joint,  so  beau- 
tifully pointed  out  by  Hilton,  where  the  fibrous  layer  of  the 
heart  sac  resembles  the  capsular  ligament,  the  serous  layer 
the  synovial  membrane,  and  the  diaphragm  the  muscle  whicli 
moves  it,  is  confirmed  by  the  similarity  of  nervous  distribu- 
tion/ We  know  that  in  pericarditis  the  patients  complain 
of  a  sense  of  constriction  and  tightness  in  the  chest,  and  are 
afflicted  with  a  shortness  of  breath  ;  we  also  see  an  inflamed 
condition  of  this  membrane  creating  a  spasm  of  the  dia- 
phragm, precisely  as  the  nerves  of  an  inflamed  joint  create  a 
contraction  of  the  adjacent  muscles  ;  and  why  are  we  not 
justified  in  attributing  these  symptoms  to  the  analogy  which 
anatomy  so  well  sustains,  and  the  axiom  of  nerve  supply  to 
joints  seems  to  confirm  ? 

CLINICAL  POINTS  PERTAINING  TO  THE  CERVICAL  NERVES. 

The  distribution  of  the  branches  of  the  upper  four  cervical 
nerves,  which  have  been  considered  in  some  detail  in  the  pre- 
ceding lecture,  may  be  said  to  furnish  sensory  filaments  to 
the  skin  covering  the  occipital  region  as  high  as  the  vertex, 
and  the  integument  of  the  neck,  in  its  posterior  and  lateral 
aspects,  as  far  down  as  the  shoulder.  The  muscular  fila- 
ments given  off  by  these  nerves  have  little  clinical  interest, 
since  the  diseases  which  are  most  frequently  met  are  confined 
chiefly  to  the  great  occipital  nerve,  the  cutaneous  branches  of 
the  neck,  and  the  phrenic.     We  will  consider,  therefore,  only 

'  Luschka  and  Ilenle  rcirard  the  phrenic  as  a  mixed  nerve.  This  view  seems  to  be 
sustained  by  cases  of  neuralgia  (as  reported  by  Falot,  Peter,  Erb,  and  others)  which  have 
been  produced  by  irritation  of  this  nerve.  The  development  of  Luschka's  ganglion  upon 
this  nerve  seems  to  be  a  further  evidence  of  the  existence  of  sensory  as  well  as  motor 
fibers  within  the  phrenic. 

^  See  axioms  of  nerve  diitributiou,  on  page  359  of  this  volume. 


GERVICO-OCGIPITAL  NEURALGIA.  373 

that  type  of  neuralgia  which  affects  the  regions  of  the  occi- 
put and  neck  called  " cervico-occipital  neuralgia"  and  the 
nervous  disorders  dependent  upon  the  distribution  of  the 
phrenic  nerve. 

Cermco-occipital  Neuralgia, — This  is  a  rare  form  of  dis- 
ease. It  is  induced  by  exposure,  perhaps,  more  frequently 
than  by  any  other  cause.  It  may  be  also  the  result  of  dis- 
eases of  the  spinal  column,  such  as  periostitis,  spondylitis  of 
tlie  cervical  region,  tumors,  and  injuries ;  also  of  wounds  of 
the  nerves,  irritation  of  the  cervical  portion  of  the  spinal 
cord,  enlarged  lymphatic  glands,  neuromata,  tumors  of  the 
neck  or  spinal  cord,  foreign  bodies,  etc.  Aneurism  of  the  ver- 
tebral artery  has  been  known  to  produce  it. 

The  pain  of  this  type  of  neuralgia  may  be  continuous  or 
[)aroxysmal,  and  either  circumscribed  or  widely  diffused  over 
tlie  entire  occipital  and  cervical  regions.  In  severe  parox- 
ysms of  pain,  the  movements  of  the  head  and  the  acts  of 
speech  and  mastication  may  be  rendered  difficult  or  impossi- 
i  )le.  Movements  of  the  head,  and  the  acts  of  laughing,  sneez- 
ing, and  mastication,  often  tend  to  excite  the  paroxysms  of 
pain.' 

As  in  many  other  forms  of  neuralgia,  certain  points  of  ex- 
1  reme  tenderness,  the  "puncta  dolorosa  of  Yalleix,"  may  be 
detected,  and  these  may  be  distinctly  located  at  the  following 
spots : 

1.  Where  the  great  occipital  nerve  escapes  at  the  occiput, 
between  the  mastoid  process  and  the  first  cervical  vertebra. 

2.  Where  the  branches  of  the  cervical  plexus  escape 
around  the  posterior  border  of  the  sterno-mastoid  muscle,  in 
t  he  middle  point  of  the  necJc.  (This  point  of  tenderness  may 
be  absent.) 

3.  Where  the  small  occipital  and  great  auricular  nerves 
''^cape  to  the  surface,  just  behind  the  mastoid  process. 

4.  Where  the  frontal  branch  of  the  trigeminus,  the  great 
auricular,  and  the  occipital  nerves  meet,  over  the  situation  of 
the  parietal  protuberance. 

^  The  fixed  attitude  in  which  this  class  of  patients  hold  their  heads  is  very  characteristic. 
26 


374  THE  SPINAL  NERVES. 

5.  Where  the  auricular  nerves  meet,  on  the  concha  of  the 
ear.' 

It  is  the  detection  of  these  points  of  tenderness '  that  as- 
sists the  diagnostician  to  discriminate  between  rheumatic 
pains  and  those  of  a  purely  neuralgic  character,  and  it  will 
usually  be  observed  that  the  paroxysms  of  pain  start  from 
these  points  of  tenderness.  This  type  of  neuralgia  is  often 
associated  with  a  similar  affection  of  the  fifth  nerve,  and  occa- 
sionally of  the  brachial  plexus.  It  may  be  followed  by  nu- 
tritive disturbances,  such  as  falling  out  of  the  hair  over  the 
affected  region.  The  duration  of  this  form  of  neuralgic  pain 
varies  from  a  few  days,  to  weeks,  months,  or  even  years,  de- 
pending somewhat  upon  the  exciting  cause. 

DISOEDERS  OF  THE   PHRENIC   NERVE. 

The  phrenic  nerve  may  manifest  the  effects  of  irritation  in 
the  form  of  neuralgia,  clonic  spasm  (hiccough),  and  tonic 
spasm  of  the  diaphragm  ;  and  also  that  of  a  more  serious  im- 
pairment of  its  function,  as  diaphragmatic  paralysis. 

Diaphragmatic  neuralgia  seems  to  be  manifested  (in 
those  few  reported  cases  w^hich  are  well  authenticated)  by  a 
pain  which  begins  in  the  base  of  the  thorax,  at  the  point  of 
insertion  of  the  diaphragm,  and  which  radiates  upward  into 
the  territory  of  the  shoulder  and  neck,  which  is  supplied  by 
the  cutaneous  branches  of  the  cervical  plexus.  The  points  of 
tenderness  which  exist  in  this  affection  seem  to  be  most 
marked  (1)  in  the  region  of  origin  of  the  phrenic,  near  to  the 
spinous  processes  of  the  middle  three  cervical  vertebrae ;  (2) 
over  the  nerve,  as  it  enters  the  supra-clavicular  fossa  ;  and  (3) 
at  the  anterior  insertions  of  the  diaphragm,  between  the 
seventh  and  the  tenth  ribs.  It  is  claimed  by  Erb  that  a  point 
of  tenderness  can  often  be  detected  over  the  cartilage  of  the 
third  rib,  but  I  find  it  difficult  to  explain  this  symptom  on 

'  This  point  of  tenderness  is  often  absent. 

*  It  will  be  noticed  that  these  points  of  circumscribed  tenderness  correspond,  in  every 
instance,  to  the  approach  of  some  nerve  or  its  terminal  filaments  to  the  surface  of  the 
body.  The  points  of  subdivision  of  a  nerve  trunk  into  its  branches  of  distribution  are  often 
the  scat  of  this  excessive  sensitiveness  to  pressure. 


DISORDERS  OF  THE  PHRENIC  NERVE,  375 

anatomical  grounds,  although  its  presence  in  some  cases 
seems  to  be  proven. 

The  pain  of  phrenic  neuralgia  is  more  or  less  continuous, 
since  the  incessant  movements  of  the  diaphragm  tend  to  ex- 
cite it ;  but  exacerbations,  of  a  character  closely  resembling 
distinct  paroxysms,  are  often  observed,  when  the  pain  be- 
comes lancinating  and  causes  impeded  respiration.  The 
efforts  of  coughing,  sneezing,  or  exertion  of  any  kind  which 
involves  the  muscles  of  the  trunk,  are  rendered  difficult  and 
painful.  Muscular  debility  and  tremblings  in  the  upper  ex- 
tremity are  sometimes  present.  As  this  type  of  neuralgia 
often  accompanies  organic  lesions  of  the  heart,  concomitant 
phenomena,  such  as  cardiac  palpitation,  angina  pectoris,  etc., 
may  coexist. 

Although  lohrenic  neuralgia  is  not  infrequently  an  inde- 
pendent and  primary  disease  in  the  anaemic  and  nervous  class 
of  patients  (especially  after  exposure  to  cold,  dampness,  etc.), 
still  it  is  far  more  commonly  met  with  as  a  concomitant  affec- 
tion of  some  other  disease.  It  is  therefore  always  best  to 
look  for  the  existence  of  heart  lesions,  aneurism  of  the  medi- 
astinum, Basedow's  disease,  angina  pectoris,  and  diseases  of 
the  liver  and  of  the  spleen,  since  they  may  explain  the 
phrenic  symptoms  and  modify  the  prognosis. 

The  close  resemblance  which  this  type  of  neuralgia  has  to 
attacks  of  diaphragmatic  pleurisy,  pericarditis,  uncomplicated 
angina  pectoris,  and  gastralgia,  makes  the  situation  of  the 
diagnostic  points  of  tenderness  an  important  factor  in  the 
discrimination. 

Violent  spasmodic  contractions  of  the  diaphragm,  termed 
clonic  spasTTi  or  '"''TiiccougJi^''^  are  accompanied  by  an  inspi- 
ratory sound,  interrupted  by  a  sudden  spasm  of  the  con- 
strictors of  the  glottis,  and  followed  by  a  short  expiration. 
The  symptoms  produced  by  this  condition  depend  upon  the 
intensity  and  duration  of  the  attack.  In  severe  cases  there 
may  be  pain,  embarrassment  of  speech,  dyspnoea,  and  retrac- 
tion of  the  epigastric  region.  The  causes  of  hiccough  may  be 
classed  under  three  heads :  1,  those  of  direct  irritation  of  the 


376  THE  SPINAL  NERVES. 

phrenic,  as  occurs  in  the  case  of  mediastinal  tumors,  aneurism 
of  the  arch,  pneumonic  or  pleuritic  inflammation,  pressure 
from  pleuritic  effusion,  etc.  ;  2,  those  of  a  reflex  nature,  as 
in  diseases  of  the  urinary  organs,  the  uterus,  and  the  intestinal 
tract  and  the  liver ;  the  irritation  of  biliary  or  renal  calculi ; 
irritation  of  the  pharynx,  oesophagus,  and  stomach ;  and  dis- 
eases of  the  peritonaeum  ;  3,  those  of  central  origin,  as  occurs 
in  hysteria,  local,  brain,  or  spinal  diseases,  blood  poisoning 
(as  in  the  fevers,  cholera,  dysentery,  etc.),  after  emotional 
excitement,  and  from  the  general  anaemia  of  nerve  centers 
after  haemorrhage.  You  can  see  from  this  list  of  causes  that 
the  symptom  of  hiccough,  if  occurring  late  in  connection  with 
any  form  of  disease,  may  be  a  most  serious  symptom. 

Tonic  spasm  of  the  diaphragm  is  a  rare  form  of  disease. 
It  has  been  called  ^'diaphragmatic  tetanus."  The  symptoms 
of  this  obscure  affection  have  been  developed  through  the  ex- 
periments of  Duchenne  upon  animals,  and  the  careful  obser- 
vations of  Yalette,  Fischl,  Yigla,  Oppolzer,  Duchenne,  and 
others  upon  man. 

The  patient  is  at  once  markedly  asphyxiated,  the  liver  is 
displaced  downward  by  the  contracted  diaphragm  ;  the  lower 
half  of  the  thorax  is  enlarged  and  rendered  immovable  ;  the 
inspirations  are  extremely  short,  and  the  expirations  are  noisy 
and  prolonged.  The  face  shows  the  evidences  of  anxiety  and 
cyanosis  ;  the  pulse  is  slow*and  diminished  in  volume ;  and 
the  voice  is  monotonous  in  tone,  and  often  interrupted. 
Acute  pains  pervade  the  lower  regions  of  the  thorax,  and 
shoot  over  the  epigastrium.  While  one  case  seems  to  have 
ended  fatally,  all  other  reported  cases  have  recovered. 

Paralysis  of  the  diaphragm  may  occur  as  a  symptom  of 
hysteria,  lead  poisoning,  the  advanced  stages  of  progressive 
muscular  atrophy,  and  paralysis  of  the  bulbar  nuclei.  It 
may  be  also  produced  by  the  extension  of  inflammation  in 
cases  of  pleurisy  or  peritonitis,  thus  creating  exudation  or 
suppuration  in  the  substance  of  the  muscle. 

When  this  condition  is  fully  developed,  the  abdominal 
walls  are  retracted  during  each  inspiratory  effort,  while  the 


THE  FOUR  LOWER   CERVICAL  NERVES.  S17 

lower  portion  of  the  thorax  is  distended  ;  in  expiration,  how- 
ever, the  hypochondriac  region,  as  well  as  the  epigastric, 
sinks  in,  while  the  chest  becomes  diminished  in  its  capacity. 
The  respiration  becomes  slow  and  difficult,  and  speaking  or 
muscular  movements  increase  the  embarrassment  of  this  func- 
tion. The  voice  is  usually  enfeebled,  and  may  be  entirely 
lost.  The  liver  tends  to  rise  in  the  chest,  during  inspiration, 
rather  than  to  be  displaced  downward  into  the  abdomen. 

THE  FOUR   LOWER   CERVICAL  ITERVES.  . 

As  was  the  case  with  the  four  upper  nerves,  which  escape 
from  the  cervical  portion  of  the  spinal  cord,  the  four  lower 
divide  into  anterior  and  posterior  divisions,  as  soon  as  they 
escape  from  the  spinal  foramina.  The  anterior  dimslons  of 
each  join  to  form  the  brachial  plexus  of  nerves,  which  sends 
filaments  of  distribution  to  the  neck,  shoulder,  upper  ex- 
tremity, and  side  of  the  thorax.  The  posterior  divisions  do 
not  form  a  plexus,*  but  are  separately  distributed  to  the  semi- 
spinalis,  complexus,  splenius,  and  trapezius  muscles,  and  then 
send  twigs  to  the  integument^  over  these  muscles,  viz.,  over 
the  region  of  the  spine  in  the  lower  part  of  the  neck. 

The  following  table '  will  assist  you  in  mastering  the  con- 
struction of  the  brachial  plexus,  and  in  understanding  the 
plates  of  that  complicated  mesh- work  of  nerves.  It  may  be 
well  to  remark  that  the  diagrams  of  this  plexus  are  seldom 
alike  in  the  works  of  any  two  authors ;  since,  if  they  are 
intended  to  be  accurate  representations  of  the  parts,  they  nat- 
urally tend  to  show  the  great  dissimilarities  which  exist  in 
the  union  of  the  different  nerves  which  help  to  form  it,  while, 
if  purely  diagrammatic,  no  two  authors  would  naturally  fol- 
low the  same  schematic  plan.  Notwithstanding  the  dissimi- 
larities which  exist,  there  are,  however,  points  of  resemblance 

^  In  the  case  of  the  three  upper  cervical  nerves,  an  anastomosis  of  the  posterior  di- 
visions occurs,  to  which  Cruveilhier  applies  the  term  "  posterior  cervical  plexus." 

'  See  researches  of  Cruveilhier,  Sappey,  Hirschfeld,  and  others. 

3  Modified  from  tables  in  "The  Essentials  of  Anatomy"  (Darling  and  Ranney). 
G.  P.  Putnam's  Sons,  New  York,  1880. 


878 


THE  SPINAL  NERVES. 


in  them  all,  which  consist  in  the  delineation  of  an  outer  cord 
formed  by  the  fifth,  sixth,  and  seventh  cervical  nerves ;  an 
inner  cord  formed  by  the  eighth  cervical  and  first  dorsal 
nerves  ;  and  a  middle  cord  formed  by  a  branch  from  both  the 
outer  and  the  inner,  which  subsequently  unite. 


THE   BRACHIAL  PLEXUS. 


Anterior 

division  of 

6th  Cek- 

vroAL 


f  Posterior  thoracic  {external  rei-pirntory  verre 
of  Bell)  distributed  to  the  serratus  inagnus 
muscle. 


Anterior 
division  of 
6th  Cer- 
vical 
nerve. 


Anterior 
division  of 
Tth  Cee- 

VICAL 

nerve. 


Anterior  ^ 
division  of 
8tu  Cer- 
vical 
nerve. 


Anterior 
division  of 

IfeT  Dor- 
sal nerve.  J 


Form 
outer 
cord  of 


Form  in- 
ner cord 
of 


)■    BRACHIAL 
PLEXUS. 


Branches 

above  the 

clavicle. 


Snpra-spinatus, 


Supra-scapu-  ;  i^^a-spinatus, 
^^^ \  Shoulder  joint. 

f  Rhomboidei  muscles  (from  .^tli 
I       cervical  nerve), 

Subclavius  (from  5th  and  Gth 
I       cervical  nerves). 
Muscular  (8)  {  g.-aleni  muscles  i  (^Ts^/,^' ^^h, 

Longus  colli      ■)  t?^^^^  ''^'": 
^  {   vical  nerves), 

I  Levator  anguli  scapula}  (from 

(.     5th  cervical  nerve). 

^  Communicating  branch  (to  phrenic  nerve). 


Branches 


f  Internal  anterior  thoracic, 
I  Internal  cutaneous, 
From  inner  '  Lesser      internal       cutaneous 

cord I      (  Wri8lerg\s  newe), 

I  Inner  head  of  median  nerve, 
[  Ulr.ar  nerve. 


helcywthe  -{  From  oixter  J  ^^^Jf "?/" Jf '5  *?°'"""^' 
plftvirlP             ftnrd  i  External  cutaneous, 

Clavicle.  cora |  ^^^^^  ^^^^  ^^  m&A\!m  nerve. 

f  1st  subscapular  nerve, 
-r, ^  ^^„^„       2d  subscapular  nerve. 


Hor^  cord. 


Musculo-spiral  ner 
l^  Circumliex  nerve 


lerva, 


This  table  and  the  diagram  (after  Gray)  shown  on  the  next 
page  will  help  to  make  clear  the  method  of  construction  of 
the  brachial  plexus,  and  the  main  branches  which  are  given 
off  from  its  different  portions.  It  will  be  perceived  that  the 
branches  of  distribution  are  subdivided  into  two  sets :  those 
given  off  above  the  line  of  the  clavicle  and  those  given  off 
below  that  line.  The  former  set,  if  traced,  will  be  seen  to 
supply  the  muscles  of  the  scapular  region,  some  of  the  mus- 
cles of  the  neck,  the  serratus  magnus  (a  muscle  of  respiration), 
and  the  subclavius.  The  branch  of  communication  which 
helps  to  complete  the  formation  of  the  phrenic  nerve  is  also 
shown  to  arise  from  the  fifth  cervical  nerve.     The  branches 

'  The  posterior  cord  of  the  brachial  plexus  is  formed  by  a  branch  from  both  the  inner 
and  outer  cord. 


THE  BRACHIAL  PLEXUS  OF  NERVES. 


379 


whicli  are  given  off  below  the  line  of  the  clavicle  are  distrib- 
uted to  the  muscles  of  the  upper  extremity,  and  will  be  con- 
sidered in  detail  in  subsequent  tables  and  diagrams. 


5tk 

Cervical.  N 


Fasciculus  FROM  4-Cerv.A/. 


— Communicating  WITH  Phrenic. 


Supra  Scapular. 
OF  Clavicle. 


Fig.  136. — A  diagram  of  the  brachial  plexus  audits  branches.     (Gray.) 

Varieties,  more  apparent  than  real,  are  frequently  met 
with  in  the  formation  of  this  plexus, '  resulting  from  the  cor- 
responding increase  or  diminution  in  the  size  of  the  above 
anastomotic  branches,  and  of  the  portion  of  the  posterior  cord 
which  is  given  off  by  the  seventh  cervical  nerve.  The  poste- 
rior cord  may  be  occasionally  formed  by  the  seventh  cervical 
nerve  alone  ;  while  it  may  in  some  instances  be  formed  by  two 
bands,  arising  from  the  fifth  and  sixth  nerves,  without  any 
assistance  from  the  seventh  nerve.     Other  variations  may  re- 

'  The  dissections  and  paper  of  11.  C.  Lucas  upon  this  point  ("  Guy's  Hospital  Eeports  " 
18V5)  and  the  description  of  this  plexus  by  Henle  seem  to  confirm  each  other  as  regards 
the  abnormalities  of  its  formation. 


380 


THE  SPINAL  NERVES, 


suit  from  the  branches  of  the  plexus  being  given  off  at  a  higher 
or  lower  point  than  usual,  and  also  by  the  seventh  nerve  join- 
ing the  plexus  at  a  higher  or  lower  level  than  normal. 

The  brachial  plexus,  as  a  whole,  is  broad  between  the  mid- 
dle and  anterior  scaleni  muscles,  at  which  point  it  lies  imme- 
diately above  the  second  portion  of  the  subclavian  artery  ;  it 
is  contracted  in  size  opposite  the  clavicle,  where  the  outer 
and  inner  cords  lie  on  the  outer  side  of  the  third  portion  of 
the  subclavian  artery ;  and,  in  the  axilla,  it  again  expands, 
the  three  cords  bearing  the  relation  to  the  second  portion  of 


Fig.  137. — Anterior  branches  of  the  four  last  cervical  and  the  first  dorsal  nerves.     (Ilirsch- 

feld.) 

1,  anterior  branch  of  the  fifth  cervical,  ordinarily  united  with  the  sixth  cervical  before  di- 
viding ;  2,  anterior  branch  of  the  sixth  cervical ;  3,  anterior  branch  of  the  seventh 
cervical;  4,  anterior  branch  of  the  eipjhth  cervical ;  5,  anterior  branch  of  xhe  first 
dorsal;  6,  origin  of  the  subclavian  nerve;  7,  posterior  thoracic  arising  from  tin 
fifth,  sixth,  and  seventh  cervical  nerves;  8,  supra-scapular;  9,  common  trunk  ol 
of  the  branches  supplying  the  levator  anguli  scapulae  and  the  rhomboidei ;  10,  supei-ior 
subscapular;  11,  anterior  thoracic  branches;  12,  inferior  subscapular:  13,  long  sub- 
scapular; 14,  separate  branch  to  the  teres  major;  15,  circumflex  nerve;  16,  lesser 
internal  cutaneous;  17,  internal  cutaneous ;  18,  ulnar;  19,  median;  20,  musculo- 
spiral;  21,  radial. 

the  axillary  artery  which  their  names  designate.     Thus  it  will 
be  perceived  that  this  plexus  has  important  surgical  relations 
with  the  last  two  portions  of  the  subclavian  artery  and  the  J 
two  upper  portions  of  the  axillary  artery.     The    terminal 
branches  of  the  three  cords  are  also  in  relation  with  the  third 


ABNORMALITIES   OF  THE  BRACHIAL  PLEXUS. 


381 


portion  of  the  axillary  artery,  since  they  almost  entirely  sur- 
round it. 

The  preceding  cut  of  the  brachial  plexus,  taken  from  the 
superb  anatomical  Avork  of  Sappey,  will  enable  you  to  con- 


FiG.  138. — Collateral  branches  of  the  brachial  plexus.  (Hirschfeld.) 
i,  arcade  formed  by  the  anastomosis  of  the  descending  branch  of  the  hypo-glossal  with 
the  internal  descending  branch  of  the  cervical  plexus ;  2,  pneumogastric  nerve ;  8, 
phrenic  nerv  e ;  4,  anterior  branch  of  the  fifth  cervical  pair ;  5,  anterior  branch  of 
the  sixth  cervical  pair  ;  6,  anterior  branch  of  the  seventh  cervical  pair  ;  7,  8,  anterior 
branch  of  the  eighth  cervical  pair  and  first  dorsal  pair ;  9,  9,  branch  to  the  subcla- 
vius  muscle  ;  10,  long  thoracic  nerve  ;  11,  nerve  to  the  pectoralis  major  giving  off  a 
filament  to  anastomose  with  that  supplying  the  pectoralis  minor;  12,  supra-scapular 
nerve  passing  under  the  coracoid  ligament;  18,  nerve  supplying  the  pectoralis  minor 
muscle;  14,  branch  supplying  the  pectoralis  minor  muscle  given  oif  f rom  the  one 
which  supplies  the  pectoralis  major  muscle ;  15,  inferior  branch  of  the  subscapularis ; 
10,  nerve  to  the  teres  major  muscle ;  17,  nerve  to  the  latissimus  dorsi  muscle;  18, 
accessory  branch  of  the  internal  cutaneous;  19,  an  anastomosis  of  this  branch  with 
the  perforating  branch  of  the  second  intercostal  nerve ;  20,  ramification  of  the  ac- 
cessory branch  of  the  internal  cutaneous  nerve ;  21,  internal  cutaneous  nerve;  22, 
ulnar  nerve  ;  23,  median  nerve  ;  24,  musculo-cutaneous  nerve  ;  25,  radial  nerve. 

trast  the  diagrammatic  plate  of  Gray '  with  the  actual  repre- 
sentation of  the  parts  under  consideration. 

'  See  page  380  of  this  volume. 


382 


THE  SPINAL  NERVES. 


COMMUNICATIONS   OF  THE   PLEXUS. 

The  brachial  plexus  communicates  with  the  cervical  plexus 
by  a  branch  which  joins  the  fourth  and  fifth  nerves,  and  by 
one  head  of  the  phrenic  nerve.  It  also  sends  filaments  to  the 
middle  and  inferior  cermcal  ganglia  of  the  sympathetic, 
and,  in  this  way,  anastomoses  with  the  corresponding  filaments 
of  the  first  dorsal  nerve. 

NERVES   OF   THE   UPPER  EXTREMITY. 


BRANCHES   OF   THE   OUTER   CORD   OF  THE   BRACHIAL   PLEXUS.' 


(      (1)  External 
anterior  tho- 
RACIC   


(2)  External 

or    MIISCULO-CU- 
TANEOUS 


Pectoralis  major. 


f  Muscular 
branches. 


Anterior 
branch. 


Posterior 
branch. 

Articular 
branch. 


Branches  of 

the  OUTER 

CORD  of  the  -l 
brachial 
plexus. 


(3)  Median  . . 


In  the 
hand, 


Coraco-brachialis, 

Biceps, 

Brachialis  anticus. 

Integument  of  the  front  of  forearm, 

Integument  of  ball  of  thumb, 

Joins  with  the  radial  nerve. 

Integument  of  radial  side  of  back  of  fore- 
arm. 

Joins  with  the  radial  nerve, 
i  Joins  with  the  external  cutaneous  branch 
(^      of  the  musculo-spiral  nerve. 


^    In  fore-  , 


To  elbow  joint. 

f  Pronator  radii  teres, 
I  Flexor  carpi  radialis, 
j  Palmaris  longus, 
[  Flexor  sublimis  digitorum. 
f  Flexor  longus  pollicis, 

Flexor    profundus   digitorum 
(its  outer  half), 

Pronator  quadratus. 


Muscu- 
lar. 

Anterior 
interosse- 
ous. 


Palmar 
cutane- 
ous. 


f  External 
branch. 


Internal 
branch. 


i  Integument  of  palm 
-    Integument 


of    the 


of    ball 
thumb. 

Abductor  pollicis, 

Opponens  pollicis, 

Flexor  brevis  pollicis  (outer 
head). 

Digital  to  thumb  (palmar  sur- 
face), 

Digital  to  index  finger  (outer 
side). 

Digital  to  contiguous  sides  of 
index,  middle,  and  ring  fin- 
gers, 

Filaments  to  the  two  outer 
lumbricales  muscles. 


'  Modified  from  a  table  in  "The  Essentials  of  Anatomy  "  (Darling  and  Ranney). 
Putnam's  Sons,  New  York,  1880. 


G.P. 


BRANCHES  OF  THE  BRACHIAL  PLEXUS. 


383 


BRANCHES   OF   THE    INNER    CORD    OF   THE    BRACHIAL   PLEXUS/ 


f  (1)  Internal  an- 

I         TERIOR  THORAC- 
IC. 


(2)  Internal  cu- 
taneous. 


(3)  Lesser  in- 
ternal CUTA- 
NEOUS. (VVris- 
bercc.) 


Anterior 
branch. 

Posterior 
branch. 


Branches  of 

the     INNER 

cord  of  the 
brachial 
plexus. 


(4)  Ulnar. 


Both   pectoral  muscles  (since  its  filaments  lie  above 
and  underneath  the  pectoralis  minor  muscle). 

Integument  of  the  anterior  surface  of  the 
inner  side  of  the  forearm  as  low  as  the 
wrist. 
Integument  of  the  posterior  surface  of  the 
inner  side  of  the  forearm  to  near  the 
wrist. 
May,  occasionally,  be  wanting  (the  intercosto-humeral 

nerve  taking  its  place). 
Integument  of  the  posterior  surface  of  the  lower  third 
of   the   arm  (joining  with   the   intercosto-humeral 
nerve  and  the  posterior  branch  of  the  internal  cu- 
taneous nerve). 

f  Articular  (to  elbow  joint) — several  small 
filaments. 

i  Flexor  carpi  ulnaris, 
Muscular.        }  Inner  half  oi  flexor  pro- 
(       fundus  digitorum. 
\  Integument    of    front    of 


In  the 
forearm. 


In  hand. 


Palmar  cuta- 
neous. 

Dorsal   cuta- 
neous. 

(^  Articular. 

Superficial 
branches. 


Deep 

branches. 


wrist  and  palm  of  hand. 
'  Integument    at    back    of 
wrist  and  one  and  one 
half    fingers    on   inner 
side  of  dorsal  surface 
of  hand. 
-{   To  wrist  joint. 
(  Palmaris  brevis, 
J    Integument  of  inner  one 
and  one  half  fingers  on 
palm. 
Muscles  of  little  finger, 
Interossei  muscles, 
The  two  inner  lumbricales. 
Adductor  pollicis, 
Flexor  brevis  pollicis  {in- 
ner head. 


The  accompanying  tables  will  afford  us  a  better  conception 
of  the  distribution  of  the  branches  of  the  three  main  cords  of 
the  brachial  plexus  than  a  long  verbal  description  ;  while  they 
will  also  enable  us,  in  studying  the  practical  points  suggested 
by  the  distribution  of  each  branch,  to  use  the  eye  as  well  as 
the  intelligence  in  following  the  subsequent  lectures.  It  is 
often  impossible  for  one,  not  previously  familiar  with  the 
detail  of  the  nerve  distribution  of  any  part,  to  appreciate  all 
the  deductions  which  may  be  drawn  by  an  author,  without 
much  labor  in  reviewing  the  preceding  text  of  the  work  which 
he  may  be  endeavoring  to  master  ;  and  I  believe  that,  in  fol- 

'  Modified  from  a  table  in  "  The  Essentials  of  Anatomy  "  (Darling  and  Ranney). 
New  York :  G.  P.  Putnam's  Sous,  1880. 


384 


THE  SPIKAL  NERVES. 


lowing  these  lectures,  these  tables  will  greatly  assist  in  such 
review,  as  well  as  in  affording  you  a  chart  which  can  be  used 
as  a  guide  to  the  preliminary  study  required  in  your  future 
attempts  to  master  other  treatises. 


BRANCHES   OF  THE   POSTERIOR   CORD   OF   THE   BRACHIAL   PLEXUS.^ 


Branches  of 

the  POSTE- 
RIOR CORD 

of  the  bra- 
chial plex- 


(1)  Subscapular 

NERVES. 


(2)  Circumflex. 


(3)  MuscuLO- 
spiral. 


The  upper ^ 

or  1st. 
The  long^ 

or  2d. 
The  lower^ 

or  8d. 
Superior 
branch. 

Inferior 
branch. 


Muscular 
branches. 


Cutaneous 
branches. 


Radial 
nerve. 


Posterior 

interosse 
ous  nerve.  i 


:l 


Subscapular  muscle. 
Latissimus  dorsi. 

Teres  major. 

Deltoid. 

Integument  over  the  back  of  the  shoulder. 

Teres  minor, 

Deltoid  (posterior  portion), 

Integument  over  the  outer  part  of  the 

shoulder. 
Triceps, 
Anconeus, 
Brachialis  anticus, 
Supinator  longus. 
Extensor  carpi  radialis  longior. 
Integument  of  the  inner  and  posterior 

portions,  and  the  outer  and  anterior 

portions  of  arm, 
Intrgum-ent  of  the  outer  aspect  of  the 

forearm. 

(Integument  of  outer  side  of 
External  J      thumb, 
branch.   |  Integument   of    ball  of    the 

1^      thumb. 
Internal    i  Integument  of  3^  fingers  on 
branch.  •<      radial   side  of   dorsum  of 

(      hand. 
All  muscles  on  back  f  Anconeus, 

of  forearm  except  ■<  Supinator  longus, 

three     .     .     .     .  (  Ext.  carp. rad.ionjr. 
Filaments  to  the  wrist  joint. 


There  are  still  some  points  pertaining  to  the  individual 
branches  of  the  brachial  plexus  which  can  not  be  shown  in  a 
tabular  arrangement,  but  which  are,  nevertheless,  important, 
as  they  will  enable  you  to  better  understand  the  surgical  and 
medical  aspects  which  are  constantly  brought  to  the  attention 
of  the  active  practitioner.  In  order  to  avoid,  as  far  as  possi- 
ble, any  important  omissions,  and  to  afford  you  a  more  prac- 
tical insight  into  the  uses  to  which  a  knowledge  of  the  nerves 
can  be  applied,  I  will  ask  you  to  follow  me  in  a  review  of  the 


'  Taken,  by  permission  of  the  publishers,  from  "  The  Essentials  of  Anatomy 
ling  and  Ilanney).     New  York  :  G.  P.  Putnam's  Sons,  1880. 


(Dar- 


THORACIC  AND  MUSCULO-CUTANEOUS  NERVES.        385 

nerves  of  the  upper  extremity,  using  the  tabulated  charts' 
as  a  means  of  reference,  should  you  become  confused  as  to 
the  source  of  origin  of  the  nerve  under  discussion,  or  fail  to 
grasp  its  subdivisions  and  their  distribution. 

THE   ANTERIOR   THORACIC    NERVES. 

These  two  nerves  are  termed  the  external  and  the  internal, 
since  one  arises  from  the  outer  cord,  and  the  other  from  the 
inner  cord  of  the  brachial  plexus.  The  external  is  sometimes 
also  called  the  superficial,  since  it  crosses  in  front  of  the  ax- 
illary artery  and  vein  to  reach  the  under  surface  of  the  great 
pectoral  muscle  ; '  while  the  internal  is  also  called  the  deep, 
since  it  passes  between  the  same  artery  and  its  accompanying 
vein,  to  be  distributed  to  the  under  surface  of  both  the  great 
and  small  pectoral  muscles.  The  two  nerves  are  connected 
with  each  other  by  a  loop  situated  on  the  inner  side  of  the 
axillary  artery.  It  is  probable  (following  the  axiom  of  Hilton 
as  to  the  cutaneous  distribution  of  nerves)  that  the  skin  over 
the  pectoral  region  receives  filaments  from  these  nerves  as 
well  as  from  the  intercostal  nerves.  As  the  pectoral  muscles 
are  agents  in  effecting  inspiration,  when  any  impediment  ex- 
ists to  breathing,  as  in  asthma,  etc.,  these  nerves  might  be 
classed  as  respiratory  in  function,  although  that  is  not  their 
most  frequent  use. 

THE   EXTERNAL   CUTANEOUS   OR    MUSCULO-CUTANEOUS    NERVE. 

This  nerve  and  its  branches  will  be  found  given  in  the 
table  of  the  subdivisions  of  the  outer  cord'  of  the  brachial 
plexus.  It  passes  through  the  belly  of  the  coraco-brachialis 
muscle  (hence  the  name  "  musculo-cutaneous  " ),  then  between 
the  biceps  and  the  brachialis  anticus  muscles,  to  a  point 
slightly  above  the  external  condyle  of  the  humerus,  where  it 
perforates  the  deep  fascia  and  divides  into  its  cutaneous 


^  See  pages  382,  383,  and  384  of  this  volume. 


^  The  anterior  fibers  of  the  deltoid  muscle  arc  said  to  be  supplied  chiefly  by  the  tho- 
racic nerves,  as  revealed  by  clinical  facts. 
2  See  page  382  of  this  volume. 


386 


THE  SPINAL  NERVES. 


branches  beneath  the  median  cephalic  vein.  Now,  a  reference 
to  the  table  of  its  distribution  will  show  you  that  three  mus- 
cles, which  move  the  arm,  are  supplied  with  motor  power  by 
means  of  this  nerve  ;  hence  we  should  expect  to  find  that  fila- 
ments would  be  sent  to  both  the  shoulder  and  elbow  joints, 
which  these  muscles  move,  and  I  am  inclined  to  think  that 


Fig.  139. — Brachial  portion  of  the  musat/o-nttancom,  median,  and  ulnar  nerves.    (Sappey.) 

1,  musculo-cutaneous  nerve  ;  2,  branch  to  the  coraco-brachialis  muscle  ;  3,  branch  to  the 
biceps  muscle ;  4,  branch  to  the  brachialis  anticus ;  5,  anastomotic  filament  which  it 
receives  from  the  median  nerve ;  6,  division  of  this  nerve  where  it  crosses  the  apo- 
neurosis of  the  arm  ;  7,  musculo-spiral  nerve  passing  between  the  brachialis  anticus 
and  supinator  longus  muscles ;  8,  external  cutaneous  branch  of  the  musculo-spiral 
nerve  ;  9,  trunk  of  the  internal  cutaneous  dividing  just  below  its  origin,  thus  giving 
off  an  accessory  branch  ;  10,  anterior  or  ulnar  branch  of  this  nerve ;  11,  brachial  por- 
tion of  the  median  and  ulnar  nerves. 


I 


small  filaments  to  the  former  joint  do  actually  exist,  although 
they  are  not  mentioned  in  the  usual  text-books  upon  anatomy. 


DISTRIBUTION  OF  MUSGULO-CUTANEOUS  NERVE.      387 

We  would  also  expect  that  any  injury '  to  the  trunk  of  this 
nerve  would  be  followed  by  paralysis  or  atrophy  of  these 
three  muscles,  as  well  as  by  a  condition  of  hyperesthesia  or 
anaesthesia  in  the  portions  of  integument  supplied  by  its  ter- 
minal filaments  (the  radial  side  of  the  forearm  and  the  ball  of 
the  thumb) ;  provided  that  the  nerve  be  irritated  or  only 
partly  destroyed,  as  shown  in  the  first  case,  or  entirely  de- 
stroyed, in  which  case  the  latter  condition  should  ensue. 

It  is  a  well-recognized  surgical  fact  that  an  inflamed  condi- 
tion of  the  elbow  joint  tends  to  create  flexion  of  the  forearm, 
by  a  contracted  state  of  the  brachialis  anticus  and  biceps 
muscles  ;  and  the  distribution  of  the  musculo- cutaneous  nerve "" 
to  the  joint,  as  well  as  to  these  two  muscles,  enables  us  now 
to  understand  why  the  irritation  of  the  articular  branches  of 
this  nerve  should  manifest  itself  in  a  contracted  state  of  the 
muscles  supplied  by  it. 

The  relation  of  this  nerve  to  the  median-cephalic  vein  will 
also  explain  why  venesection  at  the  elbow  is  liable  to  be  fol- 
lowed by  the  so-called  "bent  arm."  This  fact,  which  has 
been  explained  by  some  authors  as  the  result  of  an  injury 
done  to  the  fascia,  is  much  more  intelligently,  to  my  mind,  at- 
tributed by  Hilton  to  an  injury  done  to  the  filaments  of  the 
musculo-cutaneous  nerve,  resulting  in  a  sympathetic  contrac- 
tion of  the  flexors  of  the  elbow. 

An  exostosis  growing  from  the  humerus,  or  the  existence 
of  a  tumor  in  the  region  of  the  course  of  this  nerve,  might 
cause  a  similar  rigidity  of  the  elbow  joint,  accompanied, 
moreover,  by  a  pain  which  would  follow  the  course  of  the 
nerve  to  its  terminal  filaments.  It  has  been  suggested,  by 
the  author  above  quoted,^  to  apply  anaesthetics  over  the 
course  of  this  nerve  in  order  to  insure  relaxation  of  the 

^  Hilton  reports  a  case  where  an  officer  in  the  navy  presented  a  very  marked  instance 
of  injury  done  to  this  nerve  alone.  It  caused  paralysis  and  atrophy  of  the  three  muscles 
supplied  by  the  musculo-cutaneous  nerve  ;  but  a  perfect  recovery  took  place  in  about  two 
years,  in  spite  of  the  atrophy  which  at  first  existed. 

^  The  ulnar  nerve  also  furnishes  filaments  to  the  elbow  joint  and  supplies  the  flexor 
muscles  of  the  forearm.  This  may  also  tend  to  explain  the  surgical  fact  that  flexion 
follows  inflammation  of  the  elbow, 

^  Hilton,  op.  cit. 


388  THE  SPINAL  NERVES. 

muscles  supplied  by  it  when  the  elbow  is  thus  flexed.  Many 
cases  may  be  cited  from  different  surgical  and  medical  au- 
thors, to  illustrate  the  diagnostic  value  of  this  and  other 
nerves,  in  determining  accurately  the  seat  and  character  of 
disease  which  is  producing  distress  to  the  patient ;  but,  as 
this  aid  to  diagnosis  has  already  been  discussed  at  some 
length  in  previous  lectures,  I  will  simply  mention  it  as  an 
incentive  to  anatomical  study. 

The  cutaneous  distribution  of  this  nerve  will  be  made  clear 
by  referring  to  the  diagram  which  I  now  show  you.'  The 
clinical  value  of  the  cutaneous  nerves  has  already  been  re- 
ferred to  in  previous  lectures."  It  will  therefore  suffice  to 
again  mention,  in  this  connection,  that  hyperaesthesia,  local 
pain,  local  points  of  tenderness,  and  anaesthesia  have  often  a 
most  direct  and  positive  bearing  upon  diagnosis  ;  and  the 
axioms  given  in  the  first  lecture  upon  the  spinal  nerves  will 
prove  most  valuable  as  guides  to  the  proper  appreciation  of 
their  significance. 

It  may  strike  some  of  you  who  have  thought  deeply  con- 
cerning the  peculiarities  of  nerve  distribution,  that  this  nerve 
ought  to  stop  at  the  elbow,  since  it  has  supplied  all  of  its 
muscles  before  it  reaches  that  point,  and  has,  therefore,  appar- 
ently performed  its  function  ;  and  this  feeling  will  possibly 
be  strengthened  by  the  axiom  given  you  in  a  previous  lec- 
ture," viz.,  that  a  nerve  is  always  associated  with  that  portion 
of  the  integument  which  covers  the  points  of  insertion  of  the 
muscles  to  which  it  furnishes  motor  power.  If  you  will  ex- 
amine closely,  however,  into  the  insertion  of  the  biceps  mus- 
cle, you  will  observe  that  it  is  intimately  connected  with  the 
fascia  of  the  forearm — so  intimately  that  this  fascia  is,  in  re- 
ality, an  inherent  part  of  the  insertion  of  that  muscle.  This, 
then,  confirms  not  only  the  truth  of  the  general  axiom  given 
by  Hilton,*  but  also  explains  to  the  inquiring  mind  why  this 
nerve  should  be  continued  downward  to  the  wrist,  since  it  has 
to  do  so  in  order  to  cover  the  skin  over  one  of  the  most  impor- 

'  See  page  396  of  this  volume.  '  See  pages  359  and  3G0  of  this  volurae. 

*  Sec  page  359  of  this  volume.  ^  Op.  cit. 


DISTRIBUTION  OF  MUSCUL0-CUTANE0U8  NERVE.      3S9 

tant  points  of  insertion  of  a  muscle  wMcli  it  controls.     Other 
facts  in  the  anatomy  of  the  forearm  seem  to  still  more  beauti- 


FiG.  140. —  Cutaneous  mrves  of  the  anterior  surface  of  the  forearm  and  hand.    (Hirsch 

feld.) 

9,  epi-trochlear  branch  from  the  musculo-spiral  nerve  anastomosing  by  a  division  with 
the  antei'ior  branch  of  the  same  nerve  ;  10,  10,  anterior  branch  of  the  internal  cuta- 
neous of  the  arm  dividing  into  several  branches,  some  of  which  pass  in  front  of 
and  others  behind  the  median  basilic  vein;  11,  11,  musculo-cutaneous  nerve  crossing 
the  aponeurosis  of  the  arm  outside  of  the  tendon  of  the  biceps  muscle;  12,  12,  di- 
visions of  the  external  cutaneous  branch  of  the  radial  distributing  themselves  to  the 
skin  of  the  posterior  portion  of  the  forearm;  13,  18,  13,  divisions  which  the  anterior 
branch  of  the  internal  cutaneous  furnishes  to  the  forearm ;  14,  anastomosis  of  one 
of  these  divisions  with  a  perforating  branch  of  the  ulnar  nerve;  15,  15,  15,  termi- 
nal divisions  of  the  musculo-cutaneous  nerve;  16,  anastomosis  of  one  of  these 
divisions  with  1*7,  the  terminal  anterior  branch  of  the  radial  nerve;  18,  palmar 
cutaneous  branch  of  the  median;  19,  internal  branch  of  distribution  to  the  thumb; 
20,  external  branch  of  distribution  to  the  same ;  21,  external  branch  of  distri- 
bution to  the  index  finger;  22,  trunk  of  the  branches  of  distribution  to  the  in- 
ternal side  of  the  index  and  external  aspect  of  middle  fingers ;  23,  common  trunk 
of  distribution  to  the  internal  side  of  the  middle  and  external  side  of  the  ring 
fingers ;  24,  trunk  of  distribution  to  the  internal  side  of  the  ring  and  external  side 
of  the  little  finger ;  25,  branch  of  distribution  to  the  internal  side  of  the  little 
finger. 

27 


390  THE  SPINAL  NERVES. 

fully  confirm  this  same  general  law.  We  see  the  musculo- 
sijiral  nerve  sending  a  filament  to  nearly  the  same  region  as 
the  musciilo-cutaneous,  because  it  supplies  the  sujDinator  lon- 
gus,  which  is  situated  upon  the  outer  side  of  the  forearm ; 
while,  again,  the  internal  cutaneous  nerve  (which  properly 
may  be  considered  as  a  branch  of  the  median,  since  it  arises 
by  a  common  head)  supplies  the  skin  of  the  inner  side  of  the 
anterior  surface  of  the  forearm,  for  the  evident  reason  that 
the  muscles  supplied  by  the  median  are  extensively  attached 
to  this  same  fascia. 

CLINICAL    POINTS    PERTAINING    TO    THE    MUSCULO-CUTANEOUS 

NERVE. 

A  paralysis  limited  to  this  nerve  is  an  unusual  occurrence. 
It  may  be  produced,  however,  by  any  form  of  injury  or  of 
local  pressure  which  alone  involves  this  nerve  trunk,  and  it 
must  be  situated  in  the  region  of  the  coraco-brachialis  muscle 
to  create  impairment  of  all  of  its  filaments  of  distribution. 
Complete  paralysis  of  this  nerve  causes  total  paralysis  of  the 
biceps  and  coraco-brachialis  muscles,  but  only  a  partial  loss 
of  power  in  the  brachialis  anticus,  since  that  muscle  is  also 
furnished  with  a  filament  derived  from  the  musculo-spiral 
nerve.  The  skin  of  the  outer  border  of  the  forearm  is  also 
rendered  anaesthetic  when  this  nerve  is  injured.  As  a  result 
of  paralysis  of  the  muscles  named,  the  power  to  flex  the  fore- 
arm upon  the  arm  is  greatly  impaired,  and  would  be  totally 
lost  if  the  supinator  longus  and  a  part  of  the  brachialis  anti- 
cus muscles  were  not  capable  of  assisting  that  movement. 
These  latter  muscles,  being  supplied  by  the  musculo-spiral 
nerve,  still  retain  their  power  of  contraction ;  hence  the  diffi- 
culty in  performing  flexion  of  the  forearm  is  greater  when 
the  hand  is  supinated,  as  the  supinator  longus  no  longer  acts 
to  any  great  extent  as  a  flexor.'  The  seat  of  the  anaesthesia 
is  a  valuable  guide  to  the  nerve  affected,  as  the  musculo-cuta- 

'  The  supinator  muscle  is  an  important  aid  in  flexion  of  the  forearm,  when  the  hand 
is  pi'onafcd :  but  it  is  of  little  value  as  a  flexor  after  the  function  of  supination  has  been 
performed  by  it. 


THE  MEDIAN  NERVE. 


391 


neons  nerve  may  possibly  be  involved,  without  any  impair- 
ment of  the  other  branches  of  the  outer  cord  of  the  brachial 
plexus. 


Fi7.  141. —  Cutaneous  nerves  of  the  shoulder  and  posterior  surface  of  the  arm.     (Sappey.) 

1,  1,  terminal  ramifications  of  the  supra-acromial  branch  of  the  cervical  plexus ;  2,  cuta- 
neous branch  of  the  axillary  nerve  ;  3,  another  cutaneous  branch  of  the  same  nerve 
traversing  the  posterior  border  of  the  deltoid ;  4,  terminal  divisions  of  the  perforat- 
ing branch  of  the  second  intercostal  nerve ;  5,  perforating  branch  of  the  third  in- 
tercostal nerve  ;  6,  internal  cutaneous  branch  of  the  musculo-spiral  nerve ;  7,  epi- 
trochlear  branch  of  the  internal  cutaneous  nerve ;  8,  posterior  division  of  the  ulnar 
branch  of  the  internal  cutaneous ;  9,  external  cutaneous  division  of  the  radial 
nerve ;  10,  10,  internal  cutaneous  filament  of  the  radial  nerve. 


THE    MEDIAN"   KERVE. 

While  this  nerve  arises  by  two  heads,  derived,  respectively, 
from  the  outer  and  inner  cords  of  the  brachial  plexus,  it  has 
been  classed  as  a  branch  of  the  former.'    This  nerve  bears  a 

^  The  reader  is  referred  to  the  table  on  page  378  of  this  volume. 


392 


THE  SPINAL  NERVES. 


Fig.  142. — Cutaneous  nerves  of  the  posterior  surface  of  the  forearm  and  hand.     (Sappcy.) 

7,  epi-trochlear  branch  of  the  internal  cutaneous  nerve ;  8,  posterior  division  of  the  ulnar 
branch  of  the  internal  cutaneous ;  9,  external  cutaneous  division  of  the  radial  nerve ; 
10,  10,  internal  cutaneous  lilamcnt  of  the  radial  nerve;  11,  posterior  divi.«:ion  of  the 
anterior  terminal  or  cutaneous  branch  of  the  radial  nerve  ;  12,  first  twig  rising  from 
this  branch  (it  forms  the  external  dorsal  nerve  of  distribution  to  the  thumbs) ;  13,  sec- 
ond twig  of  the  same  division- (it  subdivides  at  the  superior  part  of  the  first  intercostal 
space — one  of  these  divisions  forms  the  internal  dorsal  cutaneous  nerve  of  the  thumb, 
the  other  ramifies  in  the  skin  of  the  dorsal  face  of  the  first  phalanx  of  the  index 
finger) ;  14,  third  branch,  which  descends  into  the  second  interosseous  space,  where 
it  bifurcates  (one  of  these  divisions  is  lost  in  the  internal  half  of  the  integument  on 
the  dorsal  surface  of  the  first  phalanx  of  the  index  finger,  and  the  other  in  the  exter 
nal  half  of  the  skin  which  covers  the  dorsal  surface  of  the  middle  finger) ;  15,  dorsal 
branch  of  the  ulnar  nerve;  16,  external  division  of  this  branch  anastomosing  with 
one  or  two  filaments  of  the  anterior  terminal  branch  of  the  radial  passing  directly 
into  the  third  interosseous  space,  where  it  divides  (one  of  these  divisions  ramifies  in  the 
internal  half  of  the  skin  which  invests  the  first  phalanx  of  the  middle  finger,  the  other 
supplies  the  first  phalanx  of  the  ring  finger);  17,  second  ramification  of  the  same 
branch,  which  also  bifurcates  under  the  fourth  interosseous  space  (one  of  these 
divisions  ramifies  in  the  skin  on  the  dorsal  surface  of  the  first  phalanx  of  the  ring 
finger,  the  other  forms  the  external  dorsal  nerve  of  distribution  to  the  little  finger) ; 
18,  internal  dorsal  nerve  of  distribution  to  the  little  finger. 


DISTRIBUTION  OF  THE  MEDIAN  NERVE.  393 

surgical  relation  to  the  hracJiial  artery^  since  it  lies,  at  first, 
upon  the  outer  side  of  that  vessel,  then  crosses  it,  and,  finally, 
reaches  its  inner  side  at  the  bend  of  the  elbow.  It  enters  the 
forearm  between  the  two  heads  of  the  pronator  radii  teres 
muscle,  passes  down  the  middle  line  of  the  anterior  surface  of 
the  forearm  till  it  reaches  the  annular  ligament  of  the  wrist, 
then  passes  underneath  the  arch  formed  by  that  ligament, 
when  it  becomes  flattened  and  expanded  in  front  of  the  flexor 
tendons  in  the  palm  of  the  hand,  and  finally  terminates  in 
branches  to  the  muscles  and  integument  of  the  hand  and 
fingers.  The  table,  which  has  been  referred  to  in  previous 
lectures,'  will  show,  more  plainly  than  a  tedious  verbal  de- 
scription, the  parts  supplied  by  this  nerve  in  the  different  por- 
tions of  its  course.  This  nerve,  in  connection  with  its  fellow, 
the  ulnar  nerve,  furnishes  motor  power  to  all  the  flexor  and 
ipronator  muscles  of  the  forearm,  and  all  the  muscles  of  the 
palm  of  the  hand  ;  the  median  supplying  all  the  muscles  on 
the  anterior  surface  of  the  forearm  but  one  and  a  half  (the 
flexor  carpi  ulnaris,  and  one  half  of  the  flexor  profundus  digi- 
torum),  and  four  and  a  half  muscles  on  the  radial  side  of  the 
palm  (as  shown  by  the  table).  Now,  as  the  ulnar  nerve  sup- 
plies all  the  rest  of  the  muscles  of  the  anterior  surface  of  the 
forearm  and  hand,  these  two  nerves  may  be  considered  as  the 
flexor  ViTidi pronator  nerves  of  those  regions.'' 

The  cutaneous  distribution  of  the  median  nerve  is  of  in- 
terest, since  it  confirms  the  axiom '  of  nerve  distribution  to  the 
integument  over  the  muscles.  We  find  that  the  median  sends 
no  cutaneous  filaments  to  the  dorsal  surface  of  the  thumb,  but 
that  it  does  supply  its  palmar  surface  ;  the  dorsal  surface  is 
covered  with  the  extensor  tendons,  which  owe  their  motor 
power  to  the  radial  n^rve,  and  the  skin  is  therefore  supplied 
from  the  same  source.  The  sides  of  the  outer  two  and  a  half 
fingers  (those  adjoining  the  thumb)  are  likewise  supplied 

'  See  page  382  of  this  volume. 

'^  In  speaking  of  the  combined  action  of  the  median  and  ulnar  nerves,  Hilton  says : 
"These  nerves,  together,  supply  all  the  flexors  of  the  wrist  joint,  fingers  and  thumb,  all 
the  pronators  of  the  radio-ulnar  joints,  and  all  the  joints  that  these  muscles  move." 

^  See  page  357  of  this  volume. 


394 


THE  SPIXAL  NERVES. 


Fig.  144.—  Terminal  portion  of  the  median 
and  ulnar  nerves.     (Sappey.) 


Fig.  143. — Brachial  portion  of  the  muscrdo- 
cutaneous^  median,  and  ulnar _  nei'ves. 
(Sappey.) 

1,  musculo-cutaneous  nerve ;  2,  branch  to  the  coraco-brachialis  muscle ;  3,  branch  to  the 
biceps  muscle ;  4,  branch  to  the  brachialis  anticus ;  5,  anastomotic  filament  which  it 
receives  from  the  median  nerve ;  (>,  division  of  this  nerve  where  it  crosses  the  apo- 
neurosis of  the  arm ;  7,  musculo-spiral  nerve  passing  between  the  brachialis  anticus 
and  supinator  longus  muscles ;  8,  external  cutaneous  branch  of  the  musculo-spiral 
nerve  ;  9,  trunk  of  the  inteVnal  cutaneous  dividing  just  below  its  origin,  thus  giving 
off  an  accessory  branch;  10,  anterior  or  ulnar  branch  of  this  nerve  ;  11,  brachial 
portion  of  the  median  and  ulnar  nerves ;  12,  antebrachial  portion,  pahnar  and  digital 
branches  of  the  same  nerve;  13,  branch  to  the  pronator  radii  teres;  14,  trunk  of 
these  anterior  muscular  branches  dividing  and  passing  to  the  muscles  to  which  they 
are  distributed;  15,  branch  to  the  flexor  profundus  digitorum;  16,  branch  to  the 
flexor  longus  poUicis  ;  17,  anterior  interosseous  branch  ;  18,  palmar  cutaneous  branch 
dividing  just  below  its  origin;  19,  muscular  branch  of  the  thenar  eminence;  20,  ex- 
ternal branch  of  distribution  to  the  thumb ;  21,  internal  branch  of  distribution  to  the 
same;  22,  external  branch  of  distribution  of  the  index  finger;  23,  common  trunk  of 
the  internal  branches  of  distribution  to  the  index  finger  and  external  to  the  middle 
finger ;  24,  internal  trunk  of  distribution  to  the  middle  and  external  branch  to  the 
ring  finger;  25,  branch  which  the  ulnar  nerve  furnishes  to  the  flexor  carpi  ulnaris; 
26,  branches  which  the  same  nerve  furnishes  to  the  two  internal  fasciculi  of  the 
flexor  profundus  digitorum;  27,  cutaneous  and  anastomotic  filament  of  the  ulnar 
nerve ;  28,  dorsal  branch  of  this  nerve  ;  20,  its  superficial  palmar  branch  ;  30,  com- 
mon  trunk  of  the  internal  branch  of  distribution  to  the  ring  and  external  branch  to 


CLINICAL  POINTS  AFFORDED  BY  MEDIAN  NERVE.    395 

the  little  finger ;  31 ;  internal  branch  of  distribution  to  the  little  finger ;  32,  deep 
palmar  branch  ;  33,  small  branch  to  the  hypo-thenar  eminence  ;  34,  branches  to  the 
muscles  of  the  fourth  interosseous  space  and  the  fourth  lumbricalis  muscle ;  35, 
branches  to  the  muscles  of  the  third  interosseous  space  and  the  third  lumbricalis 
muscle ;  36,  branches  to  the  adductor  pollicis  and  muscles  of  the  first  and  second 
interosseous  spaces. 

with  in  teg  am  en  tary  branches  from  the  median,  the  balance 
being  supplied  by  similar  branches  of  the  ulnar  nerve. 

The  two  outer  lumbricales  muscles  are  enumerated  in  the 
preceding  tables,  as  supplied  by  the  median,  and  the  remain- 
ing lumbricales  and  interossei  muscles  by  the  ulnar  nerve. 
Now,  the  method  of  insertion  of  the  tendons  of  these  muscles 
(into  the  extensor  tendon  of  the  corresponding  finger,  on  its 
dorsal  surface)  causes  these  muscles  to  Jlex  the  proximal 
phalanx^  and  extend  the  two  remaining  phalanges '  of  each 
finger.  We  find,  therefore,  that  the  nerve  branches,  which 
supply  these  muscles,  send  cutaneous  filaments  to  the  dor- 
sal surface  of  the  two  terminal  phalanges  of  the  finger  upon 
which  the  individual  muscles  act,  thus  apparently  confirming 
the  extensor  action  of  the  muscles,  since  the  distribution  of 
nerves,  derived  apparently  from  a  flexor  source,  comprises  a 
region  covered  by  the  extensor  tendons  of  the  fingers. 

CLII^ICAL   POIi^TS   PERTAIIsriNG   TO    THE   MEDIAN"   NERVE. 

The  median  nerve  is  rarely  affected  with  paralysis,  to  the 
exclusion  of  other  nerves.  If  such  a  condition  exists,  it  may 
probably  be  traced  to  some  local  injury,  such  as  cuts,  frac- 
tures of  the  humerus,  the  use  of  badly  constructed  crutches, 
contusions  over  the  course  of  the  nerve,  gunshot  wounds,  un- 
skillful venesection,  local  pressure  from  tumors,  abscess,  etc. 
It  may  possibly  be  due  to  rheumatism,  neuritis,'  neuromata, 
and  central  causes.  The  muscles  of  the  ball  of  the  thumb, 
which  are   supplied  by  this  nerve,   are  frequently  the  seat 

^  Hunter,  Cleland,  Duchenne,  Erb,  and  others  consider  the  interossei  muscles  alone  as 
extensors  of  the  two  terminal  rows  of  phalanges.  Clinical  facts  observed  in  lead  paraly- 
sis and  in  division  of  the  ulnar  nerve  seem  to  point  to  these  muscles  rather  than  to  the 
lumbricales,  although  Hilton  groups  the  lumbricales  and  interossei  muscles  as  possessing 
a  common  function. 

'^  This  condition  may  follow  any  acute  disease.  It  is  one  of  the  sequelae  of  typhoid 
fever. 


396 


THE  SPINAL  NERVES. 


of  a  progressive  muscular  atrophy  and  its  consequent  paral- 
ysis. 

From  what  has  already  been  said  respecting  the  distribu- 


11 


Fig.  145. — A  diagram  of  the  regions  of  cutaneous  net've  distribution  in  the  anlci'ior  sur- 
face of  the  upper  extremity  and  trunk.     (Modified  from  Flower.) 

1,  region  supplied  by  the  supra-clavieular  nerve  (branch  of  the  cervical  plexus) ;  2,  re- 
gion supplied  by  the  circumflex  nerve  ;  3,  region  supplied  by  the  intercosto-hunieral 
nerve ;  4,  region  supplied  by  the  intercostal  nerve  (lateral  branch) ;  5,  region  sup- 
plied by  the  lesser  internal  cutaneous  nerve  (nerve  of  Wrisberg') ;  6,  region  supplied 
by  the  musculo-spiral  nerve  (external  cutaneous  branch) ;  7,  region  supplied  by  the 
internal  cutaneous  nerve ;  8,  region  supplied  by  the  musculo-cutaneous  nei've ;  9, 
region  supplied  by  the  median  nerve  ;  10,  region  supplied  by  the  ulnar  neive ;  11, 
region  supplied  by  the  intercostal  nerve  (anterior  branch). 

tion  of  this  nerve,  we  are  prepared  to  understand  why  the 
common  flexors  of  the  fin^^ers  and  those  of  the  wrist  should 


PARALYSIS  OF  THE  MEDIAN  NERVE.  397 

show  a  loss  of  power,  in  case  the  median  be  injured,  and  the 
muscles  of  the  thumb  give  evidence  of  the  diseased  condition. 
You  will  find,  in  such  cases,  that  the  second  phalanges  of  all 
the  fingers  and  the  third  phalanges  of  the  index  and  middle ' 
fingers  can  not  be  flexed,  and  that  the  thumb  can  not  be 
flexed  or  brought  into  contact  with  the  little  finger.  On  the 
other  hand,  flexion  of  the  first  phalanx,  with  extension  of  the 
other  two,  can  be  performed  in  all  the  fingers  by  the  aid  of 
the  interossei  which  are  supplied  by  the  ulnar  nerve.  The 
position  of  the  thumb  is  peculiar;  it  is  extended  and  ad- 
ducted  and  thus  closely  applied  to  the  index  finger,  as  in  the 
hand  of  the  ape.  The  hand,  when  flexion  at  the  wrist  is 
attempted,  is  strongly  adducted  by  the  action  of  the  flexor 
carpi  ulnaris,  as  the  antagonistic  muscle  of  the  radial  side  is 
paralyzed.  The  act  of  pronation  of  the  hand  is  seriously  im- 
paired. The  inner  three  fingers  can  be  brought  into  a  par- 
tially flexed  condition,  since  the  flexor  profundus  digitorum 
muscle  is  partly  supplied  by  the  ulnar  nerve.  These  com- 
bined effects  give  to  the  hand  and  fingers,  and  especially  to 
the  thumb,  a  position  so  peculiar  that  paralysis  of  the  median 
could  hardly  be  mistaken  by  an  anatomist  for  any  other  de- 
formity. When  the  paralyzed  muscles  begin  to  show  the 
results  of  atrophy,  the  deformity  in  the  forearm  and  in  the 
ball  of  the  thumb  will  further  assist  in  the  diagnosis  of  this 
affection. 

The  anastomosis  which  exists  between  the  cutaneous  nerves 
of  the  forearm  will  possibly  tend  to  explain  the  fact  that  com- 
plete destruction  of  the  median,  ulnar,  or  radial  nerves  may 
exist  without  any  marked  loss  of  sensibility  in  the  regions 
supplied  by  the  affected  nerve.  Should  any  such  evidences 
of  disordered  sensibility  be  present,  however,  it  will  be  con- 
fined to  the  region  supplied  by  the  nerve  which  is  the  seat  of 
disease,  or  whose  conducting  power  has  been  impaired  from 
any  cause.  If  the  median,  ulnar,  or  radial  nerves  be  injured 
below  the  wrist,  the  absence  of  anastomosis  tends  to  make  the 

'  The  flexor  sublimis  digitorum  being  completely  paralyzed,  and  the  flexor  profundus 
digitorum  being  partially  deprived  of  its  motor  power. 


398  THE  SPINAL  XEEVES. 

symptom  of  anaesthesia  a  constant  and  important  guide  to  the 
nerve  affected. 

In  severe  paralysis  of  the  median  nerve,  the  first  three 
fingers '  not  infrequently  show  trophic  disturbances  in  the 
skin  and  nails,  such  as  glossy  fingers,  ulceration,  pemphigus 
vesicles,  abnormal  growth  of  hair,  etc. 

The  relation  of  the  median  nerve  to  the  brachial  artery 
gives  to  it  a  surgical  importance.  It  will  be  observed  that 
the  nerve  lies,  at  first,  to  the  outer  side  of  that  vessel ;  later 
on,  it  crosses  it,  and  finally  passes  to  the  inner  side  of  the 
artery  in  the  region  of  the  elbow. 

THE   IXTERNAL   CUTANEOUS   AND   LESSER   INTERXAL   CUTANEOUS 

NERVES. 

These  two  nerves  arise  from  the  inner  cord  of  the  brachial 
plexus,  in  common  with  the  inner  head  of  the  median  and  the 
ulnar  nerves. 

The  internal  cutaneous  nerve  accompanies  the  brachial 
artery,  lying  upon  its  inner  side  and  in  front  of  the  lesser  in- 
ternal cutaneous  nerve,  till  the  basilic  vein  pierces  the  deep 
fascia,  when  the  nerve  accompanies  the  vein  and  soon  divides 
into  an  anterior  and  posterior  branch,  whose  distribution 
will  be.  found  given  in  preceding  tables.  It  assists  the  coraco- 
humeral  nerve  in  supplying  the  integument  over  the  biceps 
muscle,  and  sends  filaments  to  the  skin  of  the  forearm  as  low 
down  as  the  wrist." 

The  lesser  internal  cutaneous  nerve,  called  also  the  nerve  of 
Wrisberg,'  has  the  same  general  origin  as  the  preceding  nerve, 
except  that  it  arises  slightly  below  it.  Like  the  former  nerve, 
it  accompanies  the  brachial  artery,  lying  upon  its  inner  side 
and  behind  the  nerve  just  described,  and,  after  its  escape 
from  the  fascia,  it  supplies  the  skin  of  the  lower  third  of  the 
arm,*  becoming  joined  to  the  posterior  branch  of  the  internal 

^  Those  adjoining  the  thumb.     Sec  figure  on  page  396  of  this  volume. 
'  See  cut  on  page  396  of  this  voUmie. 

3  For  the  region  of  cutaneous  distribution  to  this  nerve,  the  reader  is  referred  to  the 
diagrammatic  cuts  on  pages  389  and  396  of  this  volume. 
*  See  Fig.  145  of  this  volume. 


THE  ULNAR  NERVE. 


399 


Fig.  146. — Cataneoim  nerves  of  the  shoul-      Fig.   147. —  Cutaneous  nerves  of  the  anfe- 
der  and  anterior  surface  of  the  arm.  rior  surface  of  the  forearm  and  hand. 

(Hirschfeld.)  (Hirschfeld.) 

1,1,  divisions  of  the  supra-acromial  branch  of  the  cervical  plexus  ;  2,  2,  2,  terminal  rami- 
fications of  the  cutaneous  division  of  the  circumflex  nerve  ;  3,  division  of  the  inter- 
nal cutaneous  nerve  of  the  arm  ;  4,  small  filament  from  the  perforating  branch  of 
the  second  intercostal  nerve;  5,  external  cutaneous  branch  from  the  musculo-spiral- 
nerve ;  6,  internal  cutaneous  branch  crossing  the  aponeurosis  of  the  arm  ;  7,  epi- 
trochlear  branch  of  this  nerve,  anastomosing  by  a  division  with  8.  the  ulnar  nerve, 
and  9,  9,  with  the  anterior  branch  of  the  same  nerve ;  10,  10,  anterior  branch  of  the 
internal  cutaneous  of  the  arm,  dividing  into  several  branches,  some  of  which  pass  in 
front  of  and  others  behind  the  median-basilic  vein  ;  11,  11,  musculo-cutaneous  nerve 
crossing  the  aponeurosis  of  the  arm  outside  of  the  tendon  of  the  biceps  muscle  ;  12, 
12,  divisions  of  the  external  cutaneous  branch  of  the  radial,  distributing  themselves 
to  the  skin  of  the  posterior  portion  of  the  forearm  ;  13,  13,  13,  divisions  which  the 
anterior  branch  of  the  internal  cutaneous  furnishes  to  the  forearm  ;  14,  anastomosis 
of  one  of  these  divisions  with  a  perforating  branch  of  the  ulnar  nerve;  15,  15,  15, 
terminal  divisions  of  the  musculo-cutaneous  nerve;  16,  anastomosis  of  one  of  these 
divisions  with  lY,  the  terminal  anterior  branch  of  the  radial  nerve  ;  18,  palmar  cuta- 
neous branch  of  the  median  ;  19,  internal  branch  of  distribution  to  the  thumb  ;  20, 
external  branch  of  distribution  to  the  same;  21,  external  branch  of  distribution  to 
the  index  finger ;  22,  trunk  of  the  branches  of  distribution  to  the  internal  side  of  the 
index  and  external  aspect  of  middle  fingers  ;  23,  common  trunk  of  distribution  to  the 
internal  side  of  the  middle  and  external  side  of  the  ring  fingers  ;  24,  trunk  of  distri- 
bution to  the  internal  side  of  the  ring  and  external  side  of  the  little  finger ;  25, 
branch  of  distribution  to  the  internal  side  of  the  little  finger. 


400  THE  SPINAL  NERVES. 

cutaneous  nerve  or  to  the  intercosto-humeral  nerve.  The  size 
of  this  nerve  varies,  as  it  is  often  supplanted  by  the  intercos- 
to-humeral '  nerve,  which  is  then  of  extremely  large  size„  In 
this  case  the  nerve  of  Wrisberg  may  be  entirely  wanting, 
and  the  intercosto-humeral  nerve  act  independently  of  any 
communication  with  the  brachial  plexus. 

THE   ULNAR   NERVE. 

This  nerve  arises  from  the  inner  cord  of  the  brachial  plex- 
us, in  common  with  the  internal  cutaneous  and  the  nerve  of 
Wrisberg,  as  well  as  with  the  inner  head  of  the  median  nerve. 
It  bears  a  surgical  relation  with  the  third  portion  of  the  ax- 
illary artery  and  the  upper  part  of  the  brachial  artery,  since 
it  lies  internally  to  and  in  close  proximity  with  both  ;  but  it 
gradually  separates  from  the  brachial  artery  as  it  passes  down 
the  arm.  It  perforates  the  deep  fascia  of  the  arm  in  company 
with  the  inferior  profunda  branch  of  the  brachial  artery,  and 
descends  in  a  groove  between  the  olecranon  process  of  the 
ulna  and  the  inner  condyle  of  the  humerus,  until  it  enters  the 
forearm  by  passing  between  the  two  heads  of  the  flexor  carpi 
ulnaris  muscle.  In  the  forearm,  this  nerve  bears  a  relation 
with  the  ulnar  artery,  especially  in  the  middle  and  lower 
thirds  of  that  region  ;  the  artery  lying  upon  the  outer  side  of 
the  nerve.  At  the  wrist,  this  nerve  winds  around  the  outer 
side  of  the  pisiform  bone,  crosses  the  annular  ligament,  and 
divides  into  its  two  terminal  branches.  The  tabulated  ar- 
rangement of  the  branches  of  distribution  of  the  ulnar  nerve ' 
will  show  the  muscles  supplied  by  it,  both  in  the  forearm  and 
hand.  It  is  important  to  remember  that  this  nerve  gives  fila- 
ments to  both  the  elbow  and  wrist  joints,  and  that  its  cutane- 
ous branches  are  confined  to  the  fingers  and  palm  of  the 
hand. 

By  a  glance  at  the  diagrammatic  representation  of  the 
regions  of  the  integument  of  the  upper  extremity,  supplied 
by  individual  nerves  (see  Figs.  145  and  153),  you  will  per- 
ceive that  the  ulnar  nerve  supplies  the  dorsal  and  palmar 

'  A  branch  of  the  second  intercostal  nerve.  '  See  page  383  of  this  vohime. 


DISTRIBUTION  OF  THE  ULNAR  NERVE. 


401 


Fig.  148. — Brachial  portion  of  the  musculo-  FiG.  149.—  Terminal  portion  of  the  median 

cuta)icous,  median,  and  ulnar  nerves.  and  ulnar  nerves.     (Sappey.) 

(Sappey.) 

1,  musculo-cutaneous  nerve ;  2,  branch  to  the  eoraco-braehialis  muscle  ;  3,  branch  to  the 
biceps  muscle ;  4,  branch  to  the  brachialis  anticus ;  5,  anastomotic  filament  which  it 
receives  from  the  median  nerve ;  0,  division  of  this  nerve  where  it  crosses  the  apo- 
neurosis of  the  arm ;  7,  musculo-spiral  nerve  passing  between  the  brachialis  anticus 
and  supinator  longus  muscles ;  8,  external  cutaneous  branch  of  the  musculo-spiral 
nerve  ;  9,  trunk  of  the  internal  cutaneous  dividing  just  below  its  origin,  thus  giving 
off  an  accessory  branch;  10,  anterior  or  ulnar  branch  of  this  nerve  ;  11,  brachial 
portion  of  the  median  and  ulnar  nerves ;  12,  antebrachial  portion,  palmar  and  digital 
branches  of  the  same  nerve;  13,  branch  to  the  pronator  radii  teres;  14,  trunk  of 
these  anterior  muscular  branches  dividing  and  passing  to  the  muscles  to  which  they 
are  distributed;  15,  branch  to  the  flexor  profundus  digitoi-um;  16,  branch  to  the 
flexor  longus  pollicls  ;  17,  anterior  interosseous  branch ;  18,  palmar  cutaneous  bi'anch 
dividing  just  below  its  origin;  19,  muscular  branch  of  the  thenar  eminence;  20,  ex- 
ternal branch  of  distribution  to  the  thumb ;  21,  internal  branch  of  distribution  to  the 
same;  22,  external  branch  of  distribution  of  the  index  finger;  23,  common  trunk  of 
the  internal  branches  of  distribution  to  the  index  finger  and  external  to  the  middle 
finger;  24,  internal  trunk  of  distribution  to  the  middle  and  external  branch  to  the 
ring  finger ;  25,  branch  which  the  ulnar  nerve  furnishes  to  the  flexor  carpi  ulnaris ; 
26,  branches  which  the  same  nerve  furnishes  to  the  two  internal  fasciculi  of  the 
flexor  profundus  digitorum ;  27,  cutaneous  and  anastomotic  filament  of  the  ulnar 
nerve ;  28,  dor«;al  branch  of  this  nerve  ;  29,  its  superficial  palmar  branch  ;  30,  com- 
mon trunk  of  the  internal  branch  of  distribution  to  the  ring  and  external  branch  to 


402  THE  SPIXAL  XERYES. 

the  little  finger;  31;  internal  branch  of  distribution  to  the  little  finger;  32,  deep 
palmar  branch ;  33,  small  branch  to  the  hypo-thenar  eminence  ;  34,  branches  to  the 
muscles  of  the  fourth  interosseous  space  and  the  fourth  luiiibricalis  muscle ;  35, 
branches  to  the  muscles  of  the  third  interosseous  space  and  the  third  lumbricalis 
muscle ;  36,  branches  to  the  adductor  poUicis  and  muscles  of  the  first  and  second 
interosseous  spaces. 

surfaces  of  the  inner  one  and  a  half  fingers^  thus  leaving 
three  and  a  half  fingers  upon  the  palm  for  the  median  nerve, 
and  three  and  a  half  fingers  on  the  back  of  the  hand  for  the 
radial  nerve  to  supply.  Thus  the  integument  of  the  palm  is 
as  equally  divided  between  these  three  nerves  as  could  well 
be,  as  the  ulnar  has  a  total  of  three  fingers  (one  and  a  half 
on  both  the  palm  and  back  of  hand),  and  the  other  two 
nerves  three  and  a  half  fingers  each. 

CLINICAL   POINTS   OF   INTEREST   PERTAINING   TO  THE   ULNAR   NERVE. 

The  superficial  situation  of  this  nerve  in  the  arm,  near  the 
elbow  and  at  the  wrist,  would  seem  to  suggest  that  paralysis 
of  this  nerve  would  be  a  matter  of  common  occurrence,  as  it 
is  apparently  exposed  to  injury.  It  is,  nevertheless,  infre- 
quently affected  with  traumatic  paralysis.  The  causes  which 
reported  cases  show  to  have  produced  this  condition  include 
about  the  same  list  of  accidents  as  mentioned  in  connection 
with  paralysis  of  the  median  nerve ;  but  sleeping  upon  the  ann 
when  placed  beneath  the  head,  the  use  of  poorly  constructed 
crutches,  fractures  and  dislocations  at  the  shoulder,  tumors, 
contusions,  wounds  of  all  kinds,  neuritis,'  and  neuromata  are 
among  the  most  common.  Eesting  upon  the  elbow  has  been 
reported  by  Duchenne  as  a  cause  of  this  type  of  paralysis  in 
a  certain  class  of  workmen ;  and  the  so-called  '' injury  to  the 
funny  bone,"  which  consists  of  a  contusion  over  the  seat  of 
the  ulnar  nerve  at  the  elbow,  seems  to  justify  the  conclusion 
that  this  might  easily  be  the  seat  of  paralysis  from  long-con- 
tinued or  constant  pressure. 

It  is  a  rule  among  surgeons,  when  operating  about  the 
elbow  joint,'  to  guard  against  injury  to  the  ulnar  nerve,  espe- 

'  Rosenthal  states  that  this  condition  is  most  frequent  after  typhoid  fever  and  acute 
diseases. 

'  This  is  especially  important  in  excision  of  this  joint,  as  the  nerve  is  apt  to  be  injured 
in  raising  the  periosteum  from  the  bone. 


CLINICAL  POINTS  AFFORDED  BY  ULNAR  NERVE.     403 

cially  when  the  steps  of  the  operation  bring  the  knife  in 
proximity  to  the  inner  condyle  of  the  humerus. 

As  has  been  mentioned  in  connection  with  the  median  nerve, 
the  ulnar,  as  well  as  the  median  nerve,  may  be  considered  as 
a  pronator  and  flexor  nerve  of  the  wrist  and  a  flexor  nerve 
of  the  fingers,  since  the  distribution  of  the  two  is  confined 
exclusively  to  the  anterior  surface  of  the  forearm  and  the 
palmar  surface  of  the  hand.  The  table  of  the  branches  of  the 
ulnar  nerve '  will  help  us  to  readily  appreciate  the  peculiari- 
ties of  ulnar  paralysis  from  a  theoretical  standpoint,  and  to 
properly  interpret  the  phenomena  when  met  in  actual  expe- 
rience. 

We  can  see,  by  reference  to  the  table,  that  the  flexor  carpi 
ulnaris  and  the  greater  part  of  the  flexor  profundus  digito- 
rum  muscles  would  be  paralyzed,  and  that  the  muscles  of 
the  hypo  thenar  eminence,  as  well  as  the  interossei  muscles 
of  the  hand,  the  two  inner  lumbricales,  a  part  of  the  flexor 
brevis  pollicis,  and  the  adductor  poUicis  would  be  similarly 
affected.  Now,  the  clinical  evidences  of  this  form  of  paralysis 
are  in  perfect  accord  with  these  facts.  We  find  that  the  ad- 
duction of  the  hand  is  no  longer  performed  in  a  perfect  man- 
ner, since  the  flexor  carpi  ulnaris  can  no  longer  act  in  unison 
with  the  extensor  carpi  ulnaris ;  that  flexion  of  the  hand  is 
performed  imperfectly  and  by  means  of  the  flexor  of  the  ra- 
dial side  of  the  forearm  only,  since  that  muscle  is  supplied 
by  the  median  nerve  :  that  the  ability  to  move  the  little  fin- 
ger is  almost  entirely  abolished  ;  that  complete  flexion  of  the 
inner  three  fingers  is  rendered  diflicult  and  sometimes  impos- 
sible ;  that  the  fingers  can  not  be  separated  from  each  other, 
or  compressed  into  a  close  lateral  juxtaposition,  owing  to 
paralysis  of  the  interossei  muscles  ;  and  that  both  flexion  of 
the  flrst  phalanx  and  extension  of  the  two  terminal  pha- 
langes of  all  the  fingers  are  rendered  impossible,  for  the  same 
reason. 

When  the  ulnar  nerve  is  paralyzed  above  tJie  icrist^  so  that 
the  interossei  and  lumbricales  are  alone  paralyzed,  the  hand 

^  See  page  383  of  this  volume. 


404  THE  SPmAL  NERVES. 

assumes  a  diagnostic  attitude,  the  so-called  ''claw-hand,"  in 
which  the  extensor  communis  digitorum  muscle  extends  the 
first  phalanges  of  all  of  the  fingers,  while  the  other  two  rows 
of  phalanges  are  flexed  by  the  common  flexor  muscles  of  the 
fingers  (the  interossei  and  lumbricales  being  no  longer  able  to 
flex  the  first  row  of  phalanges  or  to  extend  the  two  other 
rows).  This  same  condition  of  the  hand  may,  however,  be 
produced  by  a  condition  of  progressive  muscular  atrophy  of 
these  muscles. 

It  must  be  remembered  that  this  condition,  if  dependent 
upon  ulnar  paralysis  alone,  is  more  marked  in  the  two  inner 
fingers  than  in  the  three  outer,  since  the  lumbricales  are  sup- 
plied in  part  by  the  median  nerve ;  and  this  clinical  fact  seems 
to  stamp  the  action  of  the  lumbricales  as  similar  to  that  of  the 
interossei.  Finally,  the  effects  of  ulnar  paralysis  may  be 
manifested  in  the  movements  of  the  thumb,  since  it  supj^lies 
two  muscles  which  control  it.  This  will  be  most  apparent 
when  you  instruct  the  patient  to  press  the  thumb  forcibly 
against  the  metacarpal  bone  of  the  index  finger,  or  to  adduct 
the  thumb,  since  both  of  these  motions  will  be  rendered  diffi- 
cult or  impossible. 

These  disturbances  of  motility  create  serious  disturbances 
in  those  common  functions  in  which  the  hand  is  of  the  most 
service.  Writing,  drawing,  the  playing  of  musical  instru- 
ments, etc.,  are  rendered  difficult.  The  muscles  which  are 
supplied  by  the  median  and  radial  nerves  are  still  able,  how- 
ever, to  direct  the  hand  and  fingers  in  many  acts  which  con- 
tribute to  the  comfort  of  the  patient.  In  those  cases  where 
the  muscles  of  the  thenar  eminence  (supplied  chiefiy  by  the 
median  nerve)  are  simultaneously  affected,  the  use  of  the 
hand  is  almost  entirely  abolished. 

THE  SUBSCAPULAR  NERVES. 

These  three  nerves  are  given  off  by  the  posterior  cord  of 
the  brachial  plexus.  They  are  called  the  upper,  long,  and 
lower  subscapular  nerves  by  some  authors,  while  the  numerical 
prefixes  of  first,  second,  and  third  are  applied  to  them  by 


THE  SUBSCAPULAR  NERVES.  405 

others.  As  will  be  seen  by  the  table  of  tlie  branches  of  the 
posterior  cord  of  the  brachial  plexus, '  the  first  or  upper  nerve 
supplies  the  subscapular  muscle,  the  second  or  long  nerve 
supplies  the  latissimus  dorsi,  and  the  third  or  lower  nerve 
supplies  the  teres  major,  whose  point  of  insertion  is  similar 
to  that  of  the  preceding  muscle,  since  the  tendons  of  the  two 
often  merge  into  each  other. 

]^ow,  these  three  muscles  are  agents  in  creating  certain 
movements  at  the  shoulder  joint ;  hence  it  is  to  be  presumed 
that  each  subscapular  nerve  sends  a  filament  to  that  articula- 
tion. I  am  aware  that  the  text-books  usually  give  the  credit 
of  nerve  supply  to  this  joint  to  other  sources,  since  the  fila- 
ments of  the  supra-scapular  and  circumflex  nerves  can  be 
traced  easily  to  this  articulation  on  account  of  their  large  size, 
but  I  am  not  inclined  to  believe  that  an  axiom  ^  of  nerve  sup- 
ply, so  fully  sustained  in  other  regions,  will  not  fail  to  be 
supported  by  careful  dissections  of  this  part.  The  muscles 
supplied  by  the  subscapular  nerves  are  as  important  agents 
in  the  movements  of  the  arm  at  the  shoulder  as  those  supplied 
from  the  trunks  of  the  circumflex  and  the  supra-scapular 
nerves  ;  and,  if  it  be  true  that  a  joint,  when  exhausted  or 
inflamed,  can  control  the  muscles  which  move  it  by  means  of 
a  common  nerve  supply,  the  subscapular  nerves  must  cer- 
tainly be  enumerated  as  one  of  the  sources  of  supply  to  the 
shoulder  joint. 

CLINICAL   POINTS   PEETAINING  TO   THE   SUBSCAPULAR   NERVES. 

These  nerves  are  seldom  the  seat  of  a  localized  neuralgia, 
or  of  paralysis,  except  in  connection  with  some  other  nerves 
of  the  upper  extremity.  The  situation  at  which  they  are 
given  off  from  the  brachial  plexus  (being  branches  of  the 
posterior  cord  and  imbedded  in  the  axillary  space)  is  a  safe- 
guard against  all  common  forms  of  external  violence,  while 
few  tumors  would  create  pressure  upon  these  trunks  without 
affecting  other  nerves  at  the  same  time,  and  possibly  to  an 
equal  or  greater  degree. 

J  See  page  381  of  tliis  volume.  2  gee  page  359  of  this  volume. 

28 


406  THE  SPINAL  NERVES. 

Should  the  subscapular  nerves  happen  to  become  impaired, 
the  paralysis  would  be  shown  in  those  movements  of  the  arm 
which  are  performed  chiefly  by  the  three  muscles  supplied  by 
them.  The  latissimus  dorsi  could  no  longer  bring  the  hand 
into  the  position  assumed  when  scratching  the  anal  region  (in 
which  movement  it  is  prominently  concerned),  while  the  move- 
ment of  internal  rotation  at  the  shoulder  joint  would  be  im- 
paired, on  account  of  the  paralysis  of  the  subscapularis  and 
the  teres  major,  as  well  as  that  of  the  muscle  previously 
mentioned. 

Should  these  nerves  be  the  seat  of  degeneration,  as  in  the 
case  of  progressive  muscular  atrophy,  an  alteration  in  the  size 
of  the  latissimus  dorsi  and  teres  major  muscles  would  be 
detected,  and  the  other  symptoms  characteristic  of  this 
condition  might  be  discovered,  to  a  greater  or  less  degree, 
depending  upon  the  extent  of  the  muscular  changes. 

THE   CIRCUMFLEX   NERVE. 

This  nerve  arises  from  the  posterior  cord  of  the  brachial 
plexus,  usually  in  common  with  the  musculo-spiral  nerve, 
but  sometimes  by  an  independent  communication  with  the 
posterior  cord.  It  passes  downward  and  outward  behind  the 
axillary  artery  and  upon  the  subscapularis  muscle,  then 
backward  (in  company  Avith  the  circumflex  vessels)  through 
a  quadrilateral  space  bounded  by  the  humerus,  the  teres  ma- 
jor and  minor  muscles,  and  the  long  head  of  the  triceps,* 
when  it  divides  into  its  superior  and  inferior  branch.  It 
gives  off  a  distinct  branch  to  the  shoulder  joint,  before  its  two 
terminal  branches  are  formed,  in  the  vicinity  of  the  quadri- 
lateral space,  whose  boundaries  have  been  given. 

The  superior  branch  of  the  circumflex  nerve  is  the  larger 
of  the  two  teiminal  filaments.  It  winds  around  the  neck  of 
the  humerus,  and  supplies  the  deltoid  muscle  and  the  integu- 
ment over  the  lower  portion  of  the  shoulder. 

The  inferior  branch  is  small  in  comparison  with  the  su- 
perior, and  is  distributed  to  the  teres  minor  muscle  and  the 

'  This  space  can  be  found  depicted  in  all  the  standard  text-books  upon  anatomy. 


THE  CIRCUMFLEX  NERVE. 


W. 


integument  over  the  back  part  of  the  shoulder.  The  twig, 
given  off  to  supply  the  teres  minor  muscle,  is  sometimes  fur- 
nished with  a  ganglionic  enlargement. 

•     CLINICAL   POINTS   PERTAINING   TO   THE   CIRCUMFLEX   NERVE. 
From  what  has  been  said  regarding  the  distribution  of  this 
nerve,  it  will  be  readily  understood  that  the  deltoid  and  teres 
minor  muscles,  as  well  as  the  integument  of  the  shoulder  and 


Fig.  150. —  Circumflex  and  subscapular  nerves.     (Sappey.) 

1,  tentiinal  extremity  of  the  supra-scapular  nerve  ;  2,  branch  which  this  nerve  furnishes  to 
the  supra-spinatus  muscle ;  3,  ramifications  by  which  it  terminates  in  that  muscle ; 
4,  circumflex  nerve  embracing  the  surgical  neck  of.  the  humerus  ;  5,  filament  which 
this  nerve  sends  to  the  teres  minor  muscle ;  6,  cutaneous  nerve  to  the  shoulder  ; 
V,  branches  of  the  circumflex  nerve  given  off  to  the  deltoid  muscle. 

upper  arm,  will  be  affected  by  any  impairment  of  the  circum- 
flex nerve.  A  fact  previously  mentioned,  however,  should 
not  be  lost  sight  of,  viz.,  that  the  deltoid  muscle,  in  its  an- 
terior portion,  is  supplied  by  the  anterior  thoracic  nerves ; 
hence  the  impairment  of  the  circumflex  may  not  utterly  para- 
lyze it. 

The  intimate  relations  which  this  nerve  bears  to  the 
shoulder  joint  and  the  course  which  it  takes  around  the 
neck  of  the  humerus  render  it  particularly  liable  to  injury 
from  contusions,  concussions,  blows,  or  falls  upon  the  shoul- 


408  THE  SPINAL  NERVES. 

der;  while  dislocations  of  the  humerus  from  the  scapula, 
especially  in  a  backward  direction,  are  frequently  followed 
by  deltoid  paralysis.  If  the  shoulder  joint  become  the  seat 
of  rheumatic,  or  any  other  type  of  chronic  inflammation,  the 
nerve  may  be  involved  in  a  neuritic  process,  and  thus  cau.^^ 
a  paralysis  of  the  deltoid  or  teres  minor  ;  while  the  same  re- 
sults may  also  follow  "catching  cold,"  a  neuritis  being  prob- 
ably established.  Finally,  this  type  of  paralysis  may  follow 
injury  to  the  brachial  plexus,  all  the  forms  of  central  lesions, 
lead  poisoning,  and  progressive  muscular  atrophy. 

As  paralysis  of  the  teres  minor  muscle  can  not  be  easily 
detected,  provided  the  infra-spinatus  muscle  remains  unim- 
paired, the  symptoms  of  circumflex  paralysis  are  mostly  con- 
fined to  the  inability  to  perform  the  various  movements  into 
which  the  deltoid  muscle  prominently  enters.  The  arm  can 
not  be  raised  from  contact  with  the  wall  of  the  thorax,  by  any 
attempt  on  the  part  of  the  patient,  nor  can  it  be  brought  for- 
ward and  raised.  When  an  attempt  is  made  by  the  patient 
to  raise  the  arm,  the  deltoid  fibers  do  not  contract,  but  lie 
flabby  and  loose,  which  distinguishes  it  from  an  anchylosed 
condition  of  the  shoulder,  without  the  necessity  of  communi- 
cated motion  being  resorted  to  in  order  to  make  the  diagno- 
sis. The  deltoid  region  atrophies,  and  the  shoulder  joint 
becomes  relaxed.  A  deep  groove  can  often  be  detected 
through  the  atrophied  muscle  between  the  head  of  the  hu- 
merus and  the  articular  surface  of  the  scapula. 

THE   MUSCULO-SPIRAL   NERVE. 

This  is  the  largest  branch  of  the  brachial  plexus.  It  arises 
from  the  posterior  cord,  usually  in  company  with  the  circum- 
flex nerve,  and  lies  behind  the  third  portion  of  the  axillary 
artery,  at  its  point  of  escape  from  the  brachial  plexus.  It 
subsequently  passes  behind  the  upper  part  of  the  brachial 
artery,  crosses  the  tendons  of  the  teres  major  and  latissimus 
dorsi  muscles,  accompanies  the  superior  profunda  artery  in  a 
spiral  groove  upon  the  humerus,  and,  by  passing  between  the 
supinator  longus  and  the  brachialis  anticus  muscles,  it  readies 


I 


THE  MUSCULO-SPIRAL  NERVE. 


409 


fii 

fl2 


151. — Musculo-spiral  nerve.  Fig.  152. —  Terminal  branches  of  the 

(Sappey.)  musculo-spiral  nerve.     (Sappey.) 

151. — 1,  circumflex  nerve ;  2.  filament  to  the  teres  minor  muscle ;  3,  cutaneous  branch 
of  the  circumflex ;  4,  trunk  of  the  musculo-spiral ;  5,  portion  of  this  nerve  which  cor- 
responds to  the  spinal  groove  of  the  humerus ;  6,  this  same  nerve  passing  between 
the  brachialis  anticus  and  supinator  longus  muscles  ;  7,  branch  which  the  musculo- 
spiral  furnishes  to  the  long  head  of  the  triceps  muscle ;  8,  8,  branch  to  the  internal 
portion  of  this  muscle  ;  9,  branch  to  the  external  portion  of  this  muscle;  10,  termi- 
nal branch  of  this  same  nerve  distributed  to  the  anconeus  muscle;  11,  another 
branch  of  the  same  nerve  supplying  also  the  external  portion  of  the  triceps  muscle ; 
12,  external  cutaneous  branch  of  the  musculo-spiral. 

152. — 1,  trunk  of  the  musculo-spiral  nerve  ;  2,  branch  to  the  supinator  longus  muscle ; 
3,  branch  to  the  extensor  carpi  radialis  longior;  4,  branch  to  the  extensor  carpi 
radialis  brevior ;  5,  bifurcation  of  this  trunk ;  6,  its  posterior  or  muscular  branch ; 
7,  the  same  branch  crossing  the  supinator  brevis,  to  which  it  gives  off  several  small 
branches ;  8,  its  terminal  divisions  ;  9,  anterior  or  cutaneous  branch  of  this  nerve ; 
10,  terminal  divisions  of  this  branch;  11,  musculo-cutaneous  nerve  ;  12,  12,  12,  its 
terminal  divisions  ;  13,  one  of  these  branches  which  descends  as  far  as  the  wrist,  and 
then  anastomoses  with  the  cutaneous  branch  of  the  radial. 


410  THE  SPINAL  NERVES. 

the  external  condyle  of  the  humerus,  where  it  divides  into 
two  terminal  branches,  viz.,  the  radial  and  the  posterior  in- 
terosseous nerves. 

The  table  of  the  branches  given  off  from  the  posterior  cord 
of  the  brachial  plexus,'  and  the  filaments  of  distribution  of 
each,  will  help  you  in  following  the  chief  points  of  interest 
associated  with  this  nerve.  It  will  be  perceived  that  the  main 
trunk  of  the  nerve  supplies  five  muscles,  while  the  posterior 
interosseous  branch  supplies  all  the  remaining  muscles  upon 
the  posterior  surface  of  the  forearm.  This  nerve  is,  therefore, 
essentially  an  extensor  nerve,  although  the  brachialis  anticus 
and  supinator  longus  muscles  assist  in  flexion  of  the  forearm. 
When  we  come  to  the  consideration  of  the  effects  of  paraly- 
sis of  this  nerve,  the  special  symptoms  will  help  still  further 
to  impress  upon  you  the  distribution  of  its  branches  to  mus- 
cles as  well  as  to  the  integument ;  and  the  points  of  interest, 
which  depend  upon  the  peculiar  course  of  the  main  trunk  of 
the  nerve,  will  be  made  prominent,  as  an  explanation  of  the 
frequent  occurrence  of  this  special  type  of  paralysis  in  cer- 
tain occupations. 

The  radial  branch  is  exclusively  distributed  to  the  integu- 
ment, as  is  shown  in  the  table,"  and  the  special  distribution  of 
the  branches  given  off  by  this  nerve  to  the  integument  of  the 
hand  has  been  already  discussed  at  some  length  in  a  previous 
lecture.' 

The  musculo-spiral  nerve  gives  an  articular  filament  to  the 
wrist  joint,  by  means  of  its  posterior  interosseous  branch ; 
and,  probably,  some  filaments  also  to  the  elbow  joint,  if 
we  accept  the  general  law  of  nerve  distribution  given  by 
Hilton,  so  often  quoted  in  the  preceding  lectures  of  this 
course. 

We  are  now  prepared  to  examine,  with  advantage,  the  dia- 
grammatic plates,*  in  which  the  regions  supplied  by  the  dif- 
ferent nerves  of  the  upper  extremity  are  exhibited  more 
clearly  than  a  verbal  description  could  alone  afford.      They 

'  Sec  page  384  of  this  volume.        '  See  page  384  of  this  volume. 

3  Seepage  402  of  this  volume.         **  See  cuts  on  pages  396  and  411  of  this  volume. 


DISTRIBUTION  OF  MUSCULO-SPIRAL  NERVE.  411 

will  prove  of  great  assistance  in  studying  the  tables'  in 
which  the  branches  of  the  individual  nerves  are  classified. 


Fig.  153. — A  diagram  of  the  regions  of  cutaneous  nerve  distribution  on  the  posterior  sur- 
face of  the  upper  extretnity  and  trunk. 

18,  region  supplied  by  the  second  dorsal  nerve  ;  19,  region  supplied  by  the  supra-scapular 
nerve;  20,  region  supplied  by  the  circumfcx  nerve  ;  21,  region  supplied  by  the  iniei'- 
costo-lvumeral  nerve ;  22,  region  supplied  by  the  external  cutaneous  nerve ;  23,  region 
supplied  by  the  internal  cutaneous  branch  of  the  musculo-spiral  nerve  ;  24,  region 
supplied  by  the  "  nerve  of  Wrisberg  ;  "  25,  region  supplied  by  the  lateral  branches 
of  the  intercostal  nerves ;  26,  region  supplied  by  the  internal  cutaneous  nerve ;  27,  re- 
gion supplied  by  the  musculo-cutaneous  nerve ;  28,  region  supplied  by  the  iliac  branch 
of  the  ilio-inguinal  nerve ;  29,  region  supplied  by  the  radial  nerve ;  30,  region  sup- 
plied by  the  ulnar  nerve. 

This  diagram  limits  the  distribution  of  each  nerve  with 
more  positiveness  than  can  be  well  verified,  since  the  cuta- 

'  See  tables  on  pages  383,  384,  and  385  of  this  volume. 


412  THE  SPINAL  NERVES. 

neous  filaments  of  two  nerves  may  supply  the  borders  of  any 
of  these  regions,  as  the  nerves  tend  to  overlap  each  other.  It 
is  not  well,  therefore,  to  rely  positively  upon  the  border  limits 
of  any  region  in  your  endeavors  to  detect  anaesthesia,  should 
you  suspect  a  paralytic  condition  of  any  sj^ecial  nerve,  and 
seek  this  means  of  confirming  your  diagnosis. 

The  rule  of  Hilton  would  naturally  cause  us  to  expect  that 
the  muscles  supplied  by  any  special  nerve  would  act  as  a 
guide  in  determining  the  source  of  the  cutaneous  nerve  supply 
over  the  points  of  attachments  of  those  muscles  ;  and  we  are 
not  disappointed  when  we  examine  closely  the  area  of  cuta- 
neous distribution  of  the  musculo-spiral  nerve.  This  nerve 
supplies  the  supinators  of  the  hand,  the  extensor  muscles  of 
the  elbow  Joint  and  of  the  wrist  joint,  and  the  extensor  mus- 
cles of  the  fingers  and  the  thumb  ;  hence  we  find  the  skin 
over  these  groups  of  muscles  supplied,  to  a  great  extent,  by 
the  same  nerve  which  affords  motor  power  to  the  muscles  un- 
derneath. This  fact  will  thus  help  you  to  remember  the  area 
of  distribution  of  any  nerve  to  the  skin  by  a  process  of  rea- 
soning based  upon  the  muscles  which  are  supplied  by  the  same 
nerve,  and  the  numerous  examples,  already  quoted  in  confir- 
mation of  this  general  law,  prove  that  the  deduction  drawn 
from  it  is,  in  all  cases,  approximately  accurate. 

CLINICAL   POINTS   PERTAINING   TO   THE   MUSCULO-SPIRAL   NERVE. 

The  musculo-spiral  nerve  is  more  frequently  affected  with 
paralysis  than  any  of  the  nerves  of  the  upper  extremity.  It 
is  particularly  liable  to  both  peripheral  and  central  causes  of 
Ijaralysis ;  thus,  in  cerebral  hemiplegia,  the  muscles  supplied 
by  this  nerve  are,  perhaps,  more  commonly  affected  than  those 
supplied  by  any  other  nerve,  while  paralysis  of  these  muscles 
is  common  as  the  result  of  chilling  of  the  uj)per  extremity, 
traumatism,  and  lead  poisoning. 

The  anatomical  situation  of  the  musculo-spiral  nerve  and 
the  peculiarity  of  its  course  around  the  humerus  probably  ex- 
plain the  frequent  occurrence  of  paralysis,  since  it  may  be 
easily  compressed  by  sleeping  upon  the  arm.     It  is  common 


CLINICAL  POINTS  AFFORDED  BY MUSCULO-SPIRAL  NERVE.  413 

to  meet  with  this  type  of  paralysis  in  patients  who  have  nsed 
their  arm  as  a  pillow,  or  in  drunkards  who  have  slept  in  some 
constrained  position  npon  benches,  steps,  etc.  Persons  who 
have  fallen  exhausted  and  have  rested  upon  the  arm,  and  sol- 
diers who  have  slept  upon  the  damp  ground,  often  arise  with 
this  form  of  paralysis.  It  is  stated  by  Brenner '  that  the  coach- 
men of  Kussia,  who  are  in  the  habit  of  sleeping  upon  the  box 
with  the  reins  wound  around  the  upper  arm,  are  victims  to 
this  condition ;  and  Bachon '  reports  the  same  result  as  com- 
mon among  the  water-carriers  of  Rennes,  since  they  pass  their 
arm  through  the  handle  of  the  heavy  water-pails  to  more  se- 
curely compress  them  against  the  chest.  The  habit  of  the 
Russians  of  tightly  bandaging  the  arms  of  infants  to  the  body, 
and  allowing  them  to  sleep  upon  one  side  for  long  intervals, 
seems  to  promote  the  frequent  occurrence  of  this  trouble. 

Among  the  other  forms  of  traumatism  which  conduce 
toward  this  form  of  paralysis  may  be  mentioned  the  use  of 
poorly  padded  crutches,  the  kicks  of  animals,  cuts,  stab 
wounds,  fractures  of  the  humerus,  dislocation  of  the  humerus 
at  the  shoulder  joint,  and  the  development  of  an  excessive 
amount  of  callus  after  a  fracture. 

Rheumatic  affections  and  a  neuritis  of  the  musculo-spiral 
nerve  are  reported  as  causes  by  Bernhardt  and  others ;  and 
cases  of  hysterical  origin  have  been  rarely  but  positively  au- 
thenticated. 

Finally,  lead  poisoning  must  be  mentioned  as  one  of  the 
most  common  causes  of  paralysis  of  the  muscles  supplied  by 
the  musculo-spiral  nerve.  The  existence  of  this  form  of  poi- 
soning will  have  generally  been  indicated,  previous  to  the  ap- 
pearance of  paralysis,  by  colic,  jaundice,  and  arthralgia,  as 
the  muscles  are  seldom  affected  until  the  latter  stages.  The 
extensor  communis  digitorum  muscle  is  usually  affected  first, 
and  the  paralysis  gradually  extends  to  the  other  muscles  sup- 
plied by  the  musculo-spiral  nerve.  The  muscles  of  the  arm 
are  much  less  frequently  affected  than  those  of  the  hand  and 
forearm ;  but,  in  severe  cases,  the  muscles  of  the  upper  arm, 

^  As  quoted  by  Erb.  ^  x%  quoted  by  Erb. 


414  THE  SPINAL  NERVES. 

shoulder,  and  even  those  of  the  lower  extremity,  may  become 
involved. 

It  is  difficult  as  yet  to  explain  the  apparent  predisposition 
of  lead  poisoning  to  affect  the  muscles  of  the  musculo-spiral 
region  in  preference  to  the  flexor  muscles.  Gombault,  Bern- 
hardt, Westphal,  Barwinkel,  Hitzig,  and  Lancereaux  have 
given  special  attention  to  the  subject,  and  arrived  at  no  com- 
mon ground  upon  which  they  can  all  agree.  The  condi- 
tion has  been  explained  as  the  result  of  a  venous  stasis  (Hit- 
zig), and  as  the  result  of  arterial  ischfemia  (Barwinkel) ;  both 
of  whom  regard  these  conditions  as  favoring  the  deposition 
of  lead  in  the  muscles  of  the  extensor  region  of  the  fore- 
arm. Peripheral  nerve  degeneration  has  been  claimed  as 
the  explanation  of  the  paralytic  symptoms  by  Gombault, 
Westphal,  and  Lancereaux,  and  in  this  view  the  investiga- 
tions of  Neuman,  Erb,  and  Eichhorst  coincide.  Whether  a 
spinal  origin  will  be  yet  determined  which  will  explain  the 
muscular  changes  and  the  loss  of  power,  is  yet  to  be  decided 
by  further  pathological  research. 

The  symptoms  which  characterize  this  type  of  paralysis 
have  such  a  distinctive  form  as  to  be  easily  recognizable  by 
the  physician  at  the  very  first  glance.  A  reference  to  the 
table  which  shows  the  distribution  of  the  musculo-spiral 
nerve  to  muscles'  will  help  to  explain  them.  We  see  that 
this  nerve  sends  filaments  to  the  triceps  and  brachialis  anticus 
muscles  in  the  arm,  and  to  all  the  extensor  muscles  of  the 
forearm.  In  accordance  with  this  distribution,  the  hand  is 
kept  in  a  state  of  flexion  when  this  nerve  is  paralyzed,  and 
can  not  be  raised  or  extended ;  the  thumb  is  flexed  and  ad- 
ducted  ;  and  the  fingers  are  flexed  and  cover  the  thumb. 
When  the  patient  attempts  to  extend  the  fingers,  the  interos- 
sei  and  lumbricales  muscles  alone  can  be  made  to  act,  and 
these  muscles,  as  has  been  mentioned  before,  can  only  extend 
the  two  terminal  phalanges  while  they  flex  the  basal  phalanx.' 

'  See  page  384  of  this  volume. 

5  The  explanation  of  this  fact  lies  in  the  insertion  of  the  tendons  of  these  muscles 
into  the  tendons  of  the  common  extensor  of  the  fingers. 


MUSGULO-SPIRAL  PARALYSIS. 


415 


The  thumb  and  the  index  finger  can  not  be  extended  or 
abducted ;  the  patient  can  not  supinate  the  hand  when  the 
forearm  is  extended  (this  position  being  assumed  in  or- 
der to  exclude  the  action  of  the  biceps  muscle),  nor  can 
the  forearm  be  half  bent  and  the  hand  half  supinated  by 
the  supinator  longus  muscle ;  and,  finally,  when  the  patient 
is  instructed  to  flex  the  forearm,  when  placed  in  a  position 
of  half  flexion  and  semi-prostration,  the  supinator  longus 
muscle  lies  flaccid,  and  does  not  become  tense  and  hard  as 
in  health.  The  loss  of  power  in  the  triceps  muscle  ren- 
ders it  impossible  for  the    patient  to  extend   the  forearm 


M.  external  head  of  triceps 


Musculo-spiral  nerre ^^ -I 

M.  brachialls  anticus —  ^"^     * 

M.  supinator  lonprus -. 

M.  extensor  carpi  rad.  longior 

M.  extensor  carpi  rad.  brevior    . 


Fig.  154. — The  motor  points  on  the  outer  aspect  of  the  arm. 


upon  the  arm  when  the  arm  is  first  raised  above  the  head ; 
nor  can  the  forearm  be  extended  with  the  same  degree  of 
force  as  the  healthy  side  in  any  position  of  the  arm. 
When  the  hand  is  laid  upon  the  table,  the  patient  is  un- 
able to  raise  the  hand  from  contact  with  it,  but  the  lateral 
movements  of  the  fingers   can  be  performed  as  in  health, 


416 


THE  SPINAL  NERVES. 


since  these  movements  are  controlled  by  the  interossei  mus- 
cles. The  action  of  the  flexor  muscles  of  the  wrist  seems 
feeble,  since  the  antagonistic  action  of  the  extensors  does  not 
afford  a  fixed  point  of  action ;  but,  if  the  wrist  be  forcibly 
extended  and  fixed,  it  will  be  seen  that  the  wrist  flexors  are 
not  paralyzed. 

This  form  of  paralysis  interferes  with  almost  all  of  the  nu- 
merous employments  of  daily  life,  since  the  functions  of  the 
hand  are  most  seriously  impaired.  The  patient  can  not  well 
hold  or  grasp  anything,  on  account  of  the  inability  to  perform 


7    8 


-_ :^ 


12  8  4  5  6 

Fig.  155. — The  motor  points  on  the  inner  side  of  the  arm. 

1,  m.  internal  head  of  triceps ;  2,  musculo-cutaneous  nerve ;  3,  median  nerve ;  4,  m. 
coraco-brachialis ;  5,  ulnar  nerve ;  6,  branch  of  median  nerve  for  pronator  radii 
teres ;  7,  musculo-cutaneous  nerve  ;  8,  m.  biceps  flexor  cubiti. 


the  extension  of  the  thumb  or  fingers  ;  and  the  impairment 
of  the  supinators  still  further  adds  to  the  uselessness  of  the 
hand.  The  regions  of  the  integument  supplied  by  the  mus- 
culo-spiral  nerve  exhibit  more  or  less  anaesthesia,  although 
the  extent  of  this  symptom,  like  that  of  the  muscular  pa- 
ralysis, is  modified  by  the  height  of  the  lesion,  which  affects 
the  nerve  as  well  as  by  its  character.  In  some  cases,  exten- 
sive  motor  paralysis  may  be  present  without  any  marked 


MUSCULO-SPIRAL  PARALYSIS. 


417 


disturbance  of  sensibility ;   tliis    can  only  be  explained  by 
the  presence  of  anastomosis  between  the  ciitaneous  nerves 


Fig.  156. —  Tlie  motor  points  on  the  extensor  {posterior)  aspect  of  the  forearm. 

1,  m.  supinator  longus ;  2,  m.  extensor  carpi  rad.  longior ;  3,  m.  extensor  carpi  rad.  bre- 
vier; 4,  5,  m.  extensor  communis  digitorum;  6,  m.  extensor  ossis.  met.  pol. ;  7,  m. 
extensor  primi.  internod.  pol. ;  8,  m.  first  dorsal  interosseous ;  9,  m.  second  dorsal 
interosseous;  10,  m.  third  dorsal  interosseous;  11,  m.  extensor  carpi  ulnaris;  12,  m. 
extensor  rain,  digiti;  13,  m.  extensor  secund.  internod.  pol.;  14,  m.  abduct,  min. 
digiti;  15,  m.  fourth  dorsal  interosseous. 

of  different  origins,  as  was  demonstrated  by  Tripier  and  Ar- 
loing'  upon  dogs. 

In  the  diagnosis  of  this  type  of  paralysis,  it  is  often  diffi- 
cult to  determine  the  exact  nature  and  seat  of  the  exciting 


As  quoted  by  Erb. 


418 


THE  SPINAL  NERVES. 


cause.     The  most  common  causes  are  injury,  pressure,  and 
lead  poisoning ;  but  the  existence  of  exciting  neuritis,  some 


Fig.  157. —  Tlie  motor  points  on  the  Jlexor  {anterim')  aspect  of  tlie  forearm. 

1,  median  nerve  and  branch  to  m.  pronator  radii  teres ;  2,  m.  palmaris  longus ;  3,  m, 
flexor  carpi  ulnaris :  4,  m.  flexor  sublim.  digit. ;  5,  ulnar  nerve ;  6,  m.  flex,  sublim. 
dig. ;  7,  volar  branch  of  the  ulnar  nerve  ;  8,  m.  palmaris  brevis ;  9,  m.  abductor  min. 
digit. ;  10,  m.  flexor-min.  digit. ;  11,  m.  opponens  min,  digit. ;  12,  13,  m.  lumbricales ; 
14,  m.  flexor  carpi  radialis  ;"l6,  m.  flexor  profund.  digitorum  ;  16,  m.  flexor  sublim. 
di'rilorum;  17,  m.  flex,  longus  pollicis ;  18,  median  nerve;  19,  m.  opponens  pollicis; 
20,  m.  abductor  pollicis;  21,  m.  flexor  brevis  pollicis;  22,  m.  adductor  pollicis;  23, 
m.  lirst  lumbricalis. 


cerebral  disease,  or  an  hysterical  cause,  must  be  excluded  or 
determined  by  the  concomitant  symptoms.     When  the  paral- 


THE  DORSAL  NERVES.  419 

ysis  is  due  to  local  compression,  the  triceps  muscle  is  not  usu- 
ally affected,  and  the  same  statement  applies  to  the  rheumatic 
form,  while  in  both  of  these  types  the  disturbance  of  sensi- 
bility is  most  frequently  confined  to  the  hand  alone.  In  lead 
paralysis,  the  supinator  brevis  muscle  remains  unaffected 
until  late  in  the  disease,  and  the  supinator  longus  muscle 
is  rarely  involved,  even  in  severe  forms  of  poisoning.  While 
this  can  not  be  taken  as  an  absolute  sign,  it  is  a  most 
valuable  point  in  diagnosis,  and  should  be  always  remem- 
bered. In  addition  to  the  muscular  paralysis,  lead  poison- 
ing is  often  accompanied  by  muscular  atrophy  and  swell- 
ing of  the  veins  upon  the  extensor  side  of  the  forearm ; 
while  tendinous  swellings  are  frequently  detected  in  the 
region  of  the  wrist. 

The  duration  of  paralysis  of  the  musculo-spiral  nerve  de- 
pends largely  upon  the  exciting  cause.  Lead  poisoning  pro- 
duces, in  all  cases,  an  exceedingly  slow  and  obstinate  form  of 
trouble,  and  the  paralysis  may  be  incurable  ;  ''crutch  paraly- 
sis" usually  recovers  speedily,  if  the  pressure  be  discontinued  ; 
traumatic  paralysis,  if  the  injury  be  severe,  follows  a  protract- 
ed course  ;  while  those  cases  which  depend  upon  cerebral 
origin  are  modified,  as  to  their  course  and  termination,  by  the 
character  of  the  exciting  lesion. 


THE   DORSAL  NERVES. 

The  nerves  of  the  dorsal  region  are  twelve  in  number  upon 
each  side  of  the  trunk.  They  escape  from  the  vertebral  canal 
by  means  of  foramina  between  the  dorsal  vertebrae,  and  are 
connected  to  corresponding  ganglia  of  the  sympathetic  nerve. 
Each  dorsal  nerve  is  joined  to  a  ganglion  of  the  sympathetic, 
immediately  after  its  escape  from  the  foramen  between  the 
vertebrae,  by  two  small  and  short  filaments  ;  hence,  there  are 
frequent  points  of  communication  between  the  cerebro-spinal 
and  sympathetic  systems  of  nerves  throughout  the  length  of 
the  vertebral  column.  As  has  been  stated  in  a  previous  lec- 
ture, the  first  dorsal  nerve  assists  to  form  the  brachial  plexus, 


420 


THE  SPmAL  NERVES. 


and  can  therefore  be  properly  classed  as  one  of  the  nerves  of 
the  upper  extremity  rather  than  a  nerve  of  the  trunk ;  the 
remaining  nerves  of  this  region  are  distributed  entirely  to 
the  parietes  of  the  thorax,  the  adjacent  pleura,  and  the  in- 
tegument covering  the  front,  sides,  and  back  of  the  chest, 
and  the  upper  part  of  the  abdomen. 

The  table  which  I  now  show  you  is  designed  to  make  the 
general  distribution  of  the  dorsal  nerves  easy  of  comprehen- 
sion, and  to  assist  in  reviewing  the  chief  points  of  interest 
which  are  presented  in  connection  with  the  nerves  of  this 
region. 

NERVES   OF  THE   DORSAL   REGION. 


Posterior 
divisions. 


DORSAL    , 
NERVES,  i 


Anterior 
\^   divisions. 


External   , 
branches.  ' 


Infernal 
branches. 


Six 

upper  or 

thoracic 

intercos- 

tals. 


oix 
lower  or 
tlioracico-  j 
abdomi- 
nal inter 
costals. 


In  upper 

six 
nerves. 

In  the 
lower  six 

nerves. 

In  upper 

six 

nerves. 

In  the 
lower  six 

nerves. 
Muscular 
branches. 

Lateral 
cutane- 
ous. 

Anterior 
cutane- 
ous. 
Muscular 
branches. 

Lateral 
cutaneous. 

Anterior 
cutaneous. 


Filaments  to  transvcrsalis  colli, 
Filaments  to  longissimus  dorsi, 
Filaments  to  tvachelo-mastoid, 
Filaments  to  levatores  costarum, 
Filaments  to  sacro-lumbalis, 
Filaments  to  accessorius. 
Same     muscles     as     in    preceding; 

bracket, 
Integument  of  the  back. 
Filaments  to  semispinalis  dorsi, 
Filaments  to  multifidus  spinae. 
Integument  of  back. 
Same    muscles     as     in    preceding 

bracket, 
No  cutaneous  filaments. 
Intercostals, 
Triangularis  sterni. 
Integument  of  chest  and  mammte, 
Upper    part   of    external    oblique 

muscle. 
Integument  over  upper  part  of  latis- 
simus  dorsi  and  the  scapular  re- 
gion. 

Integument  of  mammae  and  side  of 
the  chest. 

Intercostals, 

Abdominal  muscles. 

Integument  of   abdomen,  as  far  as 

the  edge  of  rectus. 
Integument  over  lower  part  of  latis- 

simus  dorsi. 
Upper  'part  of  rectus  and  integv- 

ment  in  front  part  of  abdomen. 


It  will  be  perceived  that  these  nerves,  like  those  of  the 
cervical  region,  divide  into  anterior  and  posterior  branches, 
in  the  immediate  vicinity  of  the  vertebral  column.  The  pos- 
terior divisions  supply  the  muscles  of  the  back  and  the  in- 


BISTRIBUriON  OF  THE  DORSAL  NERVES,  421 

I    .tegument  which  covers  that  region,  while  the  anterior  divis- 
il    ions  supply  the  muscles  of    respiration  and  some   of  the 


Fig.  158. —  The  intercostal  Jicrves.     (Masse.) 

The  pectoralis  major  and  minor  muscles  are  removed.  The  obliquus  externus  and  rectus 
abdominis  are  divided,  and  removed  in  some  places. 

1,  axillary  vein :  the  artery  js  removed ;  2,  portion  of  the  bi*achial  plexus  and  two  tho- 
racic branches  ;  3,  brachial  twii^  of  the  first  intercostal  nerve  ;  4,  brachial  twig  of  the 
second  intercostal  nerve ;  5,  inosculation  between  two  branches ;  6,  division  of  an 
intercostal  branch  into  7,  a  superficial  branch,  and  8,  a  deep  branch ;  9,  gluteal 
branch  of  the  twelfth  intercostal  nerve ;  10,  termination  of  the  ilio-scrotal  branch 
of  the  lumbar  plexus  ;  11,  mgulno-cutaneous  branch;  12,  twig  of  the  genito  crural 
branch;  13,  13,  portions  of  the  deep  nerves  after  they  have  become  superficial. 

abdominal  muscles,  and  the  integument  of  the  chest,  loins, 
and  abdomen.     The  intercostal  nerves  are  formed  entirely 

29 


422  THE  SPINAL  NERVES. 

from  the  anterior  divisions ;  those  arising  from  the  upper 
half  of  the  dorsal  region  being  called  the  ''thoracic "  intercos- 
tals,  while  the  lower  six  nerves  are  called  the  "thoracico- 
abdominal"  intercostal  nerves. 

The  first  and  last  dorsal  nerves  are  somewhat  peculiar  in 
their  distribution,  and  deserve  a  special  description.  The  first 
dorsal  nerve  has  no  lateral  cutaneous  branch,  since  the  branch 
which  corresponds  to  the  lateral  cutaneous  branch  of  the 
other  nerves  is  of  large  size,  and  enters  into  the  formation  of 
the  brachial  plexus.  The  continuation  of  this  nerve  along 
the  first  intercostal  space  is  of  small  size,  and  ends  in  the  an- 
terior cutaneous  nerve. 

The  last  dorsal  nerve  is  the  largest  of  the  twelve,  and  is 
usually  connected  with  the  first  lumbar  nerve  by  a  filament 
called  the  "  dorso-lumbar "  nerve,  which  descends  in  the 
substance  of  the  quadratus  lumborum  muscle.  It  com- 
municates also  with  the  hypogastric  branch  of  the  ilio-hy- 
pogastric  nerve  (a  branch  of  the  lumbar  plexus),  between 
the  internal  oblique  and  transversalis  muscles  of  the  ab- 
domen. Its  lateral  cutaneous  branch  is  very  large,  and  is 
distributed  to  the  integument  of  the  front  part  of  the  gluteal 
region. 

The  distribution  of  the  dorsal  nerves  to  the  costal  layer  of 
the  pleura  is  not  specially  designated  in  the  table,'  but  it  is  a 
fact  of  great  physiological  interest.  Hilton  draws  an  analogy 
between  the  pleura  and  a  synovial  membrane  of  a  joint ;  and 
the  intercostal  muscles  are  also  compared  by  him  to  those 
moving  a  joint.  Thus  this  author  adduces  further  proof  of 
his  general  law  of  nerve  distribution,  since  the  skin  of  the 
chest,  the  intercostal  muscles,  and  pleura  are  supplied  from 
the  same  source.  In  pursuing  this  same  line  of  reasoning 
(and  the  analogy  is  not  a  strained  one  from  a  physiological 
standpoint),  the  abdominal  muscles  might  also  be  included 
among  the  list  of  muscles  which  move  the  ribs  ;  and  the  nerve 
supply  to  them  also  would  thereby  be  explained  by  this  same 
axiom,  viz.,  that  the  nerves  which  supply  a  joint  supply  the 

^  See  page  420  of  this  volume. 


DISTRIBUTION  OF  THE  DORSAL  NERVES, 


423 


muscles  which  move  it  and  the  skin  over  the  insertions  of 
those  muscles. 

It  should  be  recollected  that  some  of  the  filaments  derived 


Fig.  159. —  The  nerves  situated  on  the  posterior  part  of  the  trunk.     (Masse.) 

Portions  of  the  trapezius,  splcnius,  complexus,  trachelo-raastoideus,  latissimus  dorsi,  and 
gluteus  maximus  muscles,  etc.,  etc.,  are  removed. 

1,  1,  1,  posterioi'  twigs  of  the  superficial  branches  of  the  intercostal  nerves;  2,  posterior 
branch  of  the  first  cervical  nerve,  or  sub-occipital ;  3,  posterior  branch  of  the  second 
cervical  nerve ;  4,  inosculation  of  this  branch  with  the  great  mastoid  branch ;  5,  5, 
posterior  branches  of  two  cervical  nerves  ;  6,  intercostal  branch  ;  7,  external  twig  of  a 
dorsal  branch  ;  8,  internal  twig  of  a  dorsal  branch  ;  9,  posterior  brajich  of  a  lumbar 
nerve ;  10,  posterior  branch  of  a  sacral  nerve. 


424  TEE  SPIXAL  NERVES. 

from  the  upper  intercostal  nerves  cross  the  axillary  space 
and  supply  the  integument  of  the  arm.  The  ''nerve  of  Wris- 
berg,"  which  has  been  described  in  connection  with  the  cuta- 
neous nerves  of  the  arm,  is  perhaps  the  most  important  of 
these  branches.  It  may  thus  be  understood  why  the  pain  of 
pleuritic  inflammation  may  be  carried  to  and  felt  in  the  region 
of  the  axilla  and  inner  arm,  and  why  distinct  points  of  tender- 
ness to  pressure  may  sometimes  be  detected  in  these  regions 
when  the  disease  is  confined  to  the  trunk. 

CLINICAL   POINTS   PERTAINING   TO  THE   DORSAL  NERVES. 

From  the  suggestions  thrown  out  as  to  the  physiological 
importance  of  nerve  distribution,  and  from  the  fact  that  the 
pleura  is  supplied  from  the  same  nerve  sources  as  the  respira- 
tory muscles  and  the  integument  of  the  chest,  abdomen,  and 
inner  arm,  some  important  clinical  lessons  may  be  drawn. 
Patients  suffering  from  pleurisy  feel  a  pain  in  the  costal 
muscles  which  compels  restricted  movement  of  the  ribs,  and 
which  limits  the  respiratory  function  largely  to  the  diaphragm. 
Now,  these  painful  cramps  and  stitches  are  independent  of 
the  pain  arising  alone  from  the  inflamed  pleural  surface,  and 
the  diminution  of  the  resj^iratory  movements  is  due  to  a  par- 
tially contractured  state  of  the  muscles  of  the  chest,  as  is  de- 
monstrated by  the  fact  that  patients  can  not  draw  a  long  breath 
if  asked  to  do  so  ;  hence,  we  may  reasonably  conclude  that 
Nature  has  so  distributed  the  nerves  to  the  pleura  as  to  en- 
able that  serous  membrane  to  control  the  muscles  which 
create  movement  of  the  adjacent  costal  surfaces,  and  thus 
insure  its  quietude  during  the  stages  of  inflammation  or 
repair.  It  is  wisely  suggested  by  Hilton,  in  this  connection, 
that  we  learn  a  lesson  in  the  treatment  of  such  cases  from 
Nature  herself,  viz.,  ''  never  to  allow  a  patient,  suffering  from 
pleurisy  or  pneumonia,  to  talk  except  in  monosyllables,  so  as 
to  avoid  a  full  inspiration." 

The  diagnostic  value  of  pain  is  well  exemplified  in  the 
region  of  the  thorax.  Persistent  pains  Mgh  up  between  the 
shoulders  are  strongly  indicative  of  diseases  of  the  heart, 


CLINICAL  POINTS  AFFORDED  BY  THE  DORSAL  NERVES  425 

aneurism  of  tlie  arch  of  the  aorta,  stricture  of  the  oesophagus, 
and  anything  which  would  tend  to  create  pressure  within  the 


11 


Fig.  160. — A  diagram,  of  the  regions  of  ciUaneous  nerve  distribution  in  the  anterior  sur- 
face of  the  upper  extremity  and  trunk.     (Modified  from  Flower.) 

1,  region  supplied  by  the  supra-clavicular  nerve  (branch  of  the  cervical  plexus) ;  2,  re- 
gion supplied  by  the  circumflex  nerve  ;  3,  region  supplied  by  the  intcrcosto-humeral 
nerve;  4,  region  supplied  by  the  intercostal  nerve  (lateral  branch) ;  5,  region  sup- 
plied by  the  lesser  internal  cutaneous  nerve  (nerve  of  Wrisbcrg) ;  6,  region  supplied 
by  the  musculo-spiral  nerve  (external  cutaneous  branch) ;  7,  region  supplied  by  the 
internal  cutaneous  nerve ;  8,  region  supplied  by  the  musculo-cutaneous  nerve ;  9, 
region  supplied  by  the  median  nerve  ;  10,  region  supplied  by  the  ulnar  nerve ;  11, 
region  supplied  by  the  intercostal  nerve  (anterior  branch). 

posterior  mediastinum/    If  we  meet  with  persistent  pain  in 
the  space  lying  between  the  middle  of  the  scapula  and  the 

^  John  Hilton,  op.  cit. 


426  THE  SPINAL  NERVES. 

lumbar  region  of  the  spine^  we  may  have  good  ground  to  sus- 
pect  the  existence  of  some  disease  of  the  abdominal  digestive 
viscera,  the  pain  being  carried  to  the  surface  probably  by 
oneans  of  the  splanchnic  nerves.'  It  is  not  uncommon  for 
disease  confined  to  the  transverse  colon  to  manifest  itself  in 
the  form  of  persistent  pain  in  the  lower  intercostal  region. 

The  frequent  occurrence  .of  cancer  in  the  mammary  region 
renders  its  detection  one  of  importance  in  its  early  stages, 
while,  in  the  later  stages,  the  pleura  and  the  glands  of  the 
axilla  and  mediastinse  may  be  secondarily  affected  with  can- 
cer tubercles.  Now,  in  these  conditions,  the  presence  of  pain 
in  the  back,  between  the  shoulders,  in  the  side  of  the  chest, 
or  down  the  inner  side  of  the  arm,  may  possibly  afford  invalu- 
able aid  in  diagnosis. 

The  distribution  of  the  sixth  and  seventh  intercostal  nerves 
to  the  skin  over  the  pit  of  the  stomach  may  be  a  useful  fact  to 
remember  in  making  a  diagnosis  of  the  cause  of  pain  in  that 
region,  since,  by  tracing  the  course  of  these  two  nerves  from 
before  backward,  and  observing  the  healthy  or  unhealthy  con- 
dition of  the  structures  near  to  which  the  nerves  would  pass — 
as  the  pleura,  ribs,  oesophagus,  aorta,  etc. — we  may  at  last 
reach  the  spine  as  the  seat  of  the  disease  which  is  producing 
pain  in  a  region  far  remote  from  the  cause  to  which  it  is  really 
due.  It  is  by  no  means  uncommon  for  spinal  affections  of  the 
mid-dorsal  region  to  manifest  themselves  by  a  pain  Avhich  is 
distressing,  and  referred  to  the  pit  of  the  stomach  ;  and  such 
an  origin  is  rendered  still  more  probable  if  present  on  both 
sides  of  the  median  line,  since  symmetrical  pains  are  especially 
characteristic  of  central  origin."  Should  such  a  pain  exist,  and 
a  marked  relief  ensue  when  the  patient  is  in  a  recumbent 
posture,  the  probability  of  spinal  origin  is  still  more  distinctly 
suggested. 

^  The  great  splanchnic  nerve  is  -connected  above  with  the  fourth,  fiftli,  and  sixth  dorsal 
nerves,  and  below  with  the  solar  plexus  and  thence  with  the  stomach,  duodenum,  liver, 
pancreas,  and  intestines.  It  seems  probable,  therefore,  that  the  pain  experienced  in  the 
region  of  the  scapula,  by  patients  afflicted  with  diseases  of  the  digestive  organs,  is  refer- 
able in  some  way  to  the  greater  splanchnic  nerve. 

2  The  reader  is  referred  to  the  general  axioms  of  nerve  distnbution,  quoted  on  pages 
359,  360,  and  361  of  this  volume. 


THE  INTERCOSTAL  NERVES.  427 

It  lias  been  stated  in  previous  lectures  that  pains  which  are 
confined  to  one  side  of  the  body  are  usually  indicative  of  an 
exciting  cause  which  is  confined  to  the  same  side,  rather  than 
of  diseased  conditions  of  the  central  nerve  ganglia.  It  is 
therefore  customary,  with  those  most  familiar  with  the  steps 
necessary  to  reach  a  scientific  diagnosis,  to  search  for  some 
cause  upon  the  same  side  of  the  body,  in  case  a  pain  exists 
which  is  not  symmetrically  developed  upon  both  sides.  I 
have  known  the  diagnosis  of  aneurism  within  the  thorax  to 
be  discovered  by  a  pain,  which  was  one-sided,  and  which  was 
the  only  symptom  which  the  patient  was  conscious  of,  where 
the  existence  of  the  tumor  would  probably  have  gone  on  un- 
detected but  for  this  valuable  guide.  A  constant  pain  in  the 
back  is  one  of  the  most  positive  signs  of  aneurism  of  the  coeliac 
axis,  and  1  question  if  the  diagnosis  of  aneurism  of  the  abdom- 
inal aorta  in  any  part  of  its  course  should  ever  be  made  unless 
this  symptom  can  be  detected. 

Pain  in  the  region  of  the  pectoral  muscle  may  indicate  some 
cause  referred  either  to  the  third  or  fourth  cervical  or  the  first 
dorsal  nerves ;  hence  we  must  look  in  two  different  localities 
for  the  exciting  lesion.  The  distribution  of  the  cervical  nerves 
to  the  fascia  covering  the  anterior  portion  of  the  chest  is  not 
sufficiently  well  recognized  by  the  profession  at  large,  and 
doubtless  many  cases  have  been  a  source  of  anxiety  to  the 
physician  which  could  have  been  easily  explained,  had  this 
point  been  impressed  upon  them. 

The  distribution  of  the  lower  intercostal  nerves  to  the  in- 
tegument covering  the  upper  part  of  the  muscles  of  the  abdo- 
men may  be  useful  in  diagnosis,  since  pain  in  this  region  of 
the  abdomen  may  be  created  by  pressure  of  fluid  in  the  pleural 
cavities,  and  by  other  lesions  situated  above  the  line  of  the 
diaphragm.  It  is  not  improbable,  therefore,  that  many  cases 
of  this  character  have  misled  the  medical  attendant  who  has 
referred  the  symptom  of  abdominal  pain  to  organs  within  the 
cavity  of  the  abdomen,  when  the  exciting  cause  was  to  be  sought 
for  within  the  chest  or  in  the  course  of  the  lower  intercostal 
nerves  \    Certainly,  successful  treatment  depends  upon  accu- 


428  THE  SPINAL  NERVES. 

racy  in  diagnosis ;  and  the  application  of  the  laws  of  nerve 
distribution  to  fine  discriminations  in  the  appreciation  of 
symptoms  is  a  guide  whose  value  and  utility  are  not  generally 
known. 

When  we  have  our  attention  called  by  a  patient  to  a  pain, 
no  matter  where  its  situation  may  chance  to  be,  we  are  positive 
that  it  can  be  traced  to  the  nerves  supplying  the  part.  Here, 
then,  we  have  a  direct  guide  to  follow  which  will  usually  lead 
us,  if  we  are  anatomists,  to  the  source  of  the  pain.  As  an  ex- 
ample of  this,  and  they  are  too  numerous  to  mention  in  detail, 
there  is  one  symptom  in  spinal  disease  which  stands  out  prom- 
inently, and  I  might  say  solicits  our  proper  appreciation  of  it, 
and  that  is  a  fixed  and  local  pain  upon  the  surface  of  the  body, 
with  or  without  exacerbations,  and  often  without  any  local  in- 
crease of  temperature  at  the  seat  of  the  disease.  I  feel  quite 
certain  that  through  the  medium  of  this  one  symptom  alone, 
if  properly  employed,  morbid  conditions  of  the  vertebrae  or 
the  spinal  cord,  its  membranes,  and  its  nerves,  may  be  often 
diagnosed  long  before  any  palpable  deformity  of  attitude  or 
gait  exists,  and  a  cure  often  effected  by  simple  rest. 

It  is  in  connection  with  the  nerves  of  the  dorsal  region  that 
pain  is  a  more  valuable  guide  than  in  almost  any  other  portion 
of  the  body.  The  subjacent  viscera,  occupying  the  thoracic 
and  abdominal  cavities,  are  constantly  manifesting  diseased 
conditions  by  pain  of  a  superficial  character  (through  the  in- 
timate communications  which  exist  between  the  splanchnic 
•and  dorsal  nerves)  at  spots  often  far  removed  from  the  excit- 
ing cause.  It  is  natural  that  the  medical  attendant,  unless 
his  attention  has  been  directed  to  this  fact,  should  attribute 
the  pain  to  some  fanciful  cause  in  the  locality  of  that  pain,  or 
to  some  general  diagnosis  of  neuralgia,  malaria,  etc.,  when  an 
anatomical  knowledge  might  direct  him  aright  both  in  diag- 
nosis and  treatment.  We  know  that  liver  disease  may  be  oc- 
casionally manifested  by  a  pain  in  the  region  of  the  right 
shoulder ;  that  gastric  and  intestinal  disorders  frequently  pro- 
duce a  constant  pain  in  the  back  between  the  scapulae ;  and 
that  tumors  of  the  viscera  may  produce  like  results  by  press- 


THE  INTERCOSTAL  NERVES. 


429 


lire  upon  the  splanchnic  nerves  or  the  solar  plexus  of  which 
they  form  a  part.     Without  such  a  knowledge  and  its  satis- 


Fig.  161. — A  diagram  of  the  regions  of  cutaneous  nerve  distribution  on  the  posterior  sur- 
face of  the  upper  extremity  and  trunk.     (Modified  from  Flower.) 

18,  region  supplied  by  the  second  dorsal  nerve  ;  19,  region  supplied  by  the  supra-scapular 
nerve;  20,  region  supplied  by  the  circumfez  nerve  ;  21,  region  supplied  by  the  intei'- 
costo-humeral  nerve ;  22,  region  supplied  by  the  external  cutaneous  nerve ;  23,  region 
supplied  by  the  internal  cutaneous  branch  of  the  musculo-spiral  nerve  ;  24,  region 
supplied  by  the  "  nerve  of  Wrisberg  "  ;  25,  region  supplied  by  the  lateral  branches 
of  the  intercostal  nerves ;  26,  region  supplied  by  the  intavial  cutaneous  nerve ;  27,  re- 
gion supplied  by  the  musculo-cutaneous  nerve ;  28,  region  supplied  by  the  iliac  branch 
of  the  ilio-inguinal  nerve ;  29,  region  supplied  by  the  radial  nerve ;  30,  region  sup- 
plied by  the  ulnar  nerve. 

factory  explanation,  would  we  be  apt  to  refer  such  pain  to 
causes  so  remote  ?    Would  we  look  for  causes  of  abdominal 


430  'ISE  SPINAL  NERVES. 

pain  in  the  region  of  the  thorax,  without  the  knowledge  that 
the  lower  intercostal  nerves  supplied  the  abdominal  muscles  \ 
The  lessons  taught  by  anatomy  are  of  a  most  practical  char- 
acter, and  worthy  of  the  study  even  of  those  old  in  the  prac- 
tice of  physic.  If  a  patient  complains  of  pain  on  the  surface 
of  the  body,  it  must  be  expressed  by  the  nerve  which  resides 
there ;  there  is  no  other  structure  that  can  express  it,  and 
somewhere  in  its  course  of  distribution,  between  its  periph- 
eral filaments  and  its  central  point  of  origin  from  the  enceph- 
alon  or  the  spinal  cord,  the  precise  cause  of  this  pain  ex- 
pressed upon  the  surface  must  be  situated. 

INTERCOSTAL    NEURALGIA. 

Those  forms  of  neuralgia  which  have  their  seat  in  the 
nerves  which  arise  from  the  dorsal  region  of  the  spinal  cord 
are  grouped  under  the  term  "dorso-intercostal"  neuralgia. 
The  exact  seat  of  the  pain  varies  not  only  with  the  special 
nerve  affected,  but  also  with  the  branch  of  the  nerve  which 
seems  to  manifest  the  most  irritation.  Thus,  if  the  upper 
two  nerves  are  involved,  the  pain  may  extend  to  the  arm  as 
well  as  the  trunk ;  if  the  posterior  branches  of  the  dorsal 
nerves  be  alone  involved,  the  pain  will  be  perceived  in  the 
back  and  loins  ;  and,  finally,  if  the  anterior  branches  be  alone 
the  seat  of  pain,  it  will  be  confined  to  the  intercostal  spaces 
and  the  anterior  region  of  the  chest.  It  is  rare  to  find  the 
anterior  and  posterior  branches  of  any  dorsal  nerve  simulta- 
neously affected  with  neuralgia.  The  anterior  branches  are 
usually  the  ones  which  suffer,  and  the  pain  assumes  a  type 
which  is  properly  called  ''intercostal." 

Intercostal  neuralgia  is  more  common  in  women  than  in 
men,  and  chiefly  affects  weak,  hysterical,  and  ansemic  sub- 
jects. It  appears  often  in  those  who  are  convalescing  from 
some  severe  type  of  disease.  The  causes  to  which  this  fomi 
of  neuralgia  can  be  traced  include  exposure  to  cold  or  damp- 
ness, anatomical  changes  in  the  nerves  themselves,  diseases  of 
some  of  the  adjoining  organs  (especially  in  connection  with 
phthisis),  embarrassment  to  the  venous  return  of  the  affected 


INTERCOSTAL  NEURALGIA.  431 

region,  dilatation  of  the  venous  plexuses  of  the  interior  of  the 
vertebral  canal,  aortic  aneurisms  (which  lead  to  absorption  of 
the  vertebrae  or  ribs),  all  possible  diseases  of  the  vertebrae 
themselves,  and  also  of  the  ribs,  diseases  of  the  spinal  cord, 
and  malarial  affections. 

This  form  of  neuralgia  is  most  common  upon  the  left  side, 
and  Henle  has  attributed  this  clinical  fact  to  the  arrangement 
of  the  intercostal  veins  of  the  left  side, '  which  relatively  tends 
to  impede  the  return  of  blood  upon  the  left  in  contrast  to  the 
right  side.  From  the  extensive  list  of  causes  which  have  been 
given — and  many  of  the  subdivisions  of  each  have  been 
omitted — it  can  be  readily  understood  that,  to  make  an  accu- 
rate diagnosis  as  to  the  etiology  of  intercostal  neuralgia,  is 
never  possible  without  a  most  thorough  physical  examination 
of  the  subjacent  organs,  the  bones  of  the  thorax,  and  the  con- 
ditions of  the  soft  tissues. 

The  symptoms  of  this  disease  are  generally  confined  to  the 
anterior  and  lateral  walls  of  the  trunk,  more  rarely  to  the 
tack  and  the  loins.  The  area  of  the  pain  indicates  the  nerves 
effected,  which  is  often  a  point  of  great  value  in  searching  for 
the  cause.  While  the  pain  is  of  a  burning,  dull,  and  persist- 
ent character  for  the  greater  part,  yet  it  is  often  characterized 
by  paroxysms  of  tearing  and  lancinating  pains  which  follow 
the  course  of  the  nerves  affected  with  a  remarkable  precision. 
The  violence  of  these  paroxysms  may  be  very  great,  so  as  to 
cause  syncope.  All  respiratory  motions,  such  as  sneezing, 
coughing,  blowing  the  nose,  etc.,  increase  the  pain,  and  the 
skin  is  sensitive  to  the  slightest  pressure,  even  the  weight  of 
the  bedclothes  distressing  the  patient,  although  firm  pressure 
may  sometimes  afford  relief.  While  the  paroxysm  is  active, 
the  patients  sit  with  the  body  inclined  toward  the  affected 
side,  and  their  faces  indicate  the  most  extreme  anxiety. 
They  neither  dare  to  speak  loudly  nor  take  a  deep  inspira- 
tion, on  account  of  the  pain  induced  by  such  efforts. 

'  The  intercostal  veins  of  the  left  side  empty  into  the  left  superior  intercostal  vein  or 
the  left  vena  azygos  ;  in  cither  case,  the  blcod  takes  a  circuitous  route  to  the  superior 
vena  cava. 


432  THE  SPIXAL  KERVES. 

In  intercostal  neuralgia,  as  in  most  other  forms,  there  are 
certain  points  which  are  particularly  sensitive  to  pressure, 
and  are  of  great  aid  in  confirming  the  diagnosis.  These 
points  comprise,  first,  one  near  to  the  vertebral  column  {verte- 
bral point\  where  the  nerve  emerges  from  the  inter- vertebral 
foramen  ;  secondly,  one  at  about  the  middle  of  the  entire 
course  of  the  nerve,  corresponding  to  a  line  dropped  from 
the  center  of  the  axillary  space  {lateral  point),  where  the 
lateral  branch  emerges  beneath  the  integument ;  and,  thirdly, 
one  in  front,  near  to  the  sternal  border  {anterior  or  sternal 
point\  where  the  anterior  perforating  branch  emerges  be- 
neath the  skin. 

For  some  unknown  reason,  the  intercostal  nerves,  when 
inflamed,  are  particularly  liable  to  be  associated  with  the 
appearance  of  that  form  of  skin  disease  called  "herpes  zos- 
ter." This  may  or  may  not  be  accompanied  by  neuralgic 
symptoms,  but  it  is  a  valuable  sign  of  a  neuritis  of  the  nerves 
supplying  the  region  affected. 

The  diagnosis  of  intercostal  neuralgia  can  often  be  made 
only  with  extreme  difficulty.  That  rheumatic  affection  of 
the  muscles  of  the  chest  commonly  called  "  pleurodynia"  is 
often  confounded  vdth  it,  and .  the  diagnosis  is  to  be  made 
chiefly  by  the  presence  of  the  localized  points  of  tenderness 
mentioned,  and  the  rapid  disappearance  of  all  symptoms  in 
the  course  of  a  few  days,  which  is  seldom  observed  in  true 
intercostal  neuralgia.  Pleurisy  is  also  to  be  differentiated 
from  this  disease  chiefly  by  its  physical  symptoms  ;  and  an- 
gina pectoris  is  to  be  told  by  the  phenomena  presented  by 
the  heart  and  the  pulse,  as  well  as  by  the  sense  of  impending 
death,  threatened  suffocation,  intense  anxiety,  and  the  fact 
that  the  pain  frequently  shoots  down  the  left  arm. 

NEUEALGIA   OF  THE   MAMMARY   GLAND    (mASTODYXIA). 

The  skin  over  the  mammary  gland  is  supplied  by  the  an- 
terior and  lateral  branches  of  the  second,  third,  fourth,  fifth, 
and  sixth  intercostal  nerves,  and  by  some  filaments  derived 
from  the  supra-clavicular  nerves,  while  the  glandular  struct- 


PARALYSIS  OF  THE  DORSAL  NERVES  433 

lire  itself  is  supplied  by  the  lateral  perforating  branches  of 
the  fourth,  fifth,  and  sixth  intercostal  nerves.  This  region  is 
(SiDecially  liable  to  an  extreme  form  of  neuralgia,  first  de- 
scribed by  Sir  Astley  Cooper  under  the  name  of  "irritable 
In-east."  So  intense  is  the  pain  in  some  cases  of  this  affection 
that  it  is  compared  to  the  sensation  of  cutting,  tearing,  or 
stabbing  the  part  with  a  knife.  It  is  usually  paroxysmal  in 
character,  and  generally  of  short  duration,  although  such 
attacks  may  last  for  some  hours. 

This  affection  seems  to  be  associated  with  pregnancy, 
anaemia,  chlorosis,  hysteria,  and  the  development  of  neu- 
romata upon  the  nerves  of  this  region.  It  may  be  persistent 
and  remain  for  years,  and  is  particularly  obstinate  to  treat- 
ment. 

The  detection  of  painful  points  is  to  be  looked  for  in  the 
region  of  the  escape  of  the  nerves  which  supply  the  part  from 
the  inter- vertebral  foramina  ;  and,  in  some  instances,  the  ex- 
istence of  similar  points  may  be  detected  upon  the  breast, 
near  the  nipple,  and  upon  the  sides  of  the  gland.  The  at- 
tacks are  particularly  liable  to  exacerbate  during  the  men- 
strual periods,  and,  during  the  height  of  the  paroxysm,  the 
pain  may  be  transmitted  by  other  nerves  into  the  neck,  down 
the  arm,  and  over  more  extended  areas  upon  the  chest  and 
back. 

PAEALYSIS   OF   THE   DORSAL   NERVES. 

The  dorsal  muscles  control,  to  a  great  extent,  the  move- 
ments, fixation,  and  upright  position  of  the  vertebral  column, 
but  these  conditions  require  such  a  complexity  of  muscular 
action  that  it  is  often  difficult,  in  case  of  paralysis,  to  exactly 
decide  as  to  the  muscles  which  are  affected.  Various  degrees 
of  weakness  of  the  dorsal  muscles  are  often  present  in  youth, 
sometimes  on  one  side  and  sometimes  on  the  other,  and  oc- 
casionally affecting  the  whole  back  to  a  greater  or  less  ex- 
tent. 

These  paretic  states  are  dependent  upon  rheumatic  affec- 
tions, diseases  or  injuries  of  the  vertebral  column,  disturb- 
ances of  the  motor  regions  of  the  cerebrum,  lesions  of  the 


434  TEE  SPINAL  NERVES. 

various  ganglia  of  the  encephalon,  and  lesions  of  the  kinesodic 
system  of  the  spinal  cord.  In  paraplegia,  the  motor  paralysis 
often  extends  upward  to  the  muscles  of  the  trunk ;  while, 
in  progressive  muscular  atrophy,  the  muscles  of  the  dorsal 
region  are  not  infrequently  involved. 

If  the  muscles  of  both  sides  of  the  back  be  paralyzed,  the 
spinal  column  gradually  tends  to  assume  the  condition  of  a 
posterior  curvature  (paralytic  kyphosis),  and  the  deformity  is 
usually  most  marked  in  the  dorsal  region,  as  the  lumbar  and 
cervical  regions  exhibit  it  to  a  less  degree  on  account  of  their 
anatomical  peculiarities.  If  the  extensor  muscles  of  the  back 
be  markedly  affected,  the  spinal  column  forms  an  equable 
curve,  as  if  the  body  were  bent  forward  as  in  old  age,  and  the 
patient  becomes  unable  to  voluntarily  straighten  the  trunk  to 
its  normal  posture.  When  passive  straightening  is  attempted, 
the  spine  is  easily  brought  into  its  proper  curve  ;  and  this  is  a 
point  of  diagnosis  between  paralytic  kyphosis  and  the  de- 
formity dependent  upon  structural  disease  of  the  vertebrae  or  a 
state  of  muscular  contracture. 

The  muscles  most  frequently  affected  are  the  sacro-lum- 
balis  and  the  latissimus  dorsi.  If  they  be  paralyzed  upon  one 
side  only,  the  deformity  assumes  the  type  of  scoliosis,  as  a 
lateral  curvature  is  produced  by  the  muscles  of  the  unaffected 
side.  In  this  case,  as  in  the  one  before  cited,  the  patient  is 
unable  to  rectify  the  deformity  by  any  voluntary  muscular 
effort,  although  the  spinal  curve  can  be  easily  removed  by 
mechanical  aid. 

When  the  extensor  muscles  of  the  lumbar  region  are 
markedly  impaired,  the  attitude  assumed  by  the  patient  is 
very  characteristic.  It  consists  of  a  bending  of  the  upper 
portion  of  the  trunk  in  a  backward  direction,  so  as  to  com- 
pensate for  the  bending  forward  of  the  lumbar  vertebrse  ;  this 
bending  of  the  thorax  backward  brings  the  upper  part  of  the 
body  behind  the  center  of  gravity  of  the  whole  body,  and  the 
balance  is  preserved  exclusively  by  the  action  of  the  muscles 
of  the  abdomen.  ^Vhen  the  body  is  brought  too  far  forward, 
it  sinks  and  falls,  as  the  lumbar  muscles  fail  to  support  it  in 


P ABA  LYSIS   OF  TEE  DORSAL  NERVES 


435 


an  erect  posture.  The  patient  can  not  then  bring  the  trunk 
into  its  former  posture  without  the  use  of  the  hands,  which 
are  employed  in  a  sort  of  a  climbing  process,  the  hands  being 


Fig.  162. — llie  lumbar  plexus.     (Hirschfeld.) 

lumbar  and  sacral  portions  of  the  great  sympathetic ;  2,  twelfth  dorsal  pair ;  3,  first 
lumbar  pair ;  4,  4',  ilio-hypogastric  branch ;  5,  5',  ilio-inguinal  branch ;  6,  second 
lumbar  pair;  7,  origin  of  the  geni  to-crural  branch;  7,  this  same  branch  appearing 
and  descending  in  front  of  the  psoas  muscle ;  8,  origin  of  the  external  cutaneous 
nerve;  8',  this  same  branch  leaving  the  border  of  the  psoas,  and  dividing  at  the 
level  of  the  fold  of  the  groin  ;  9,  third  lumbar  pair  ;  10,  fourth  lumbar  pair ;  11,  fifth 
lumbar  pair  ;  12,  lumbo-sacral  trunk  ;  13,  gluteal  branch  of  the  iliohypogastric ;  14, 
its  abdominal  branch ;  15,  its  genital  branches ;  16,  external  cutaneous  passing  under 
Poui)art's  ligament,  between  the  anterior  superior  and  inferior  spines  of  the  ilium ; 
17,  17,  17,  divisions  of  this  branch;  17',  point  of  origin  of  these  divisions  ;  18,  18', 
genital  branch  of  the  genito-crural  nerve;  19,  19,  femoral  division  of  this  nerve 
piercing  the  fascia  lata  in  the  neighborhood  of  the  saphenous  opening ;  19',  this 
division  exposed  at  the  fold  of  the  groin,  to  show  its  relations  with  the  femoral  artery 
and  the  saphenous  vein;  20^  20',  anterior  crural  nerve;  21,  21',  obturator  nerve. 


placed  upon  the  legs ;  a  series  of  peculiar  movements  of  the 
shoulders  and  trunk  then  follow,  which  are  employed  to  assist 


436  TEE  SPINAL  NERVES. 

the  arms  in  tossing  tlie  trunk  backward  to  an  extent  sufficient 
to  allow  the  abdominal  muscles  once  more  to  support  it.  This 
difficulty  in  bringing  the  trunk  above  the  level  of  the  lower 
limbs  is  typical  of  this  condition,  but  there  are  still  other  ad- 
ditional points  of  diagnostic  value.  The  lumbar  region  pre- 
sents a  deep  hollow  ;  the  head  is  bent  forward  in  standing  or 
walking ;  and  the  trunk  may  be  seen  to  have  a  remarkable 
oscillating  movement  when  the  patient  walks.  When  the 
patient  sits  down,  the  upper  portion  of  the  body  seems  to 
sink,  and  the  spine  presents  a  condition  of  kyphosis.  In  fact, 
it  seems  hardly  possible  that  the  condition  can  be  mistaken 
by  one  well  versed  in  anatomy. 


THE  LUMBAK  NERVES. 

The  lumbar  nerves  comprise  five  pairs  which  escape  from 
the  intervertebral  foramina  of  that  region.  Like  all  the  spi- 
nal nerves,  they  each  divide,  immediately  after  their  escape, 
into  anterior  and  posterior  divisions,  the  former  of  which  has 
a  larger  proportion  of  motor,  while  the  latter  has  an  excess  of 
sensory  fibers.  These  nerves  are  of  special  interest,  from  the 
fact  that  the  anterior  divisions  of  the  four  upper  nerves  assist 
to  form  the  lumbar  plexus.  This  plexus  is  situated  in  the 
substance  of  the  psoas  muscle,  in  front  of  the  transverse  pro- 
cesses of  the  lumbar  vertebrae.  It  is  narrow  above,  where  it 
is  joined  to  the  last  dorsal  nerve,  but  below  it  becomes 
broad,  and  is  connected  with  the  sacral  plexus  by  means  of 
the  lumbo-sacral  cord  and  a  filament  from  the  fourth  lum])ar 
nerve.  The  table  which  I  now  show  you  will  give  you  an 
opportunity  of  contrasting  the  relative  arrangement  of  the 
anterior  and  posterior  divisions  of  the  lumbar  nerves,  as  well 
as  of  studying  the  origin  of  the  seven  main  nerve  trunks 
given  off  from  the  lumbar  plexus. 

In  the  following  table  the  formation  of  the  lumhar  plexui 
is  shown,  as  well  as  the  branches  which  are  given  off  from 
each  nerve  which  assists  to  form  it. 


THE  LUMBAR  NERVES. 


437 


TABLE    OF   THE    XEKVES    OF   THE   LUMBAR    REGION. 


r 

External 
\  branches. 


Posterior  divisions. 


1st  Lumbar 
nerve. 


Lumbar    j 

NERVKS.    ] 


Anterior 
divisions 


Interned 
branches. 


2d   Lumbar 
nerve. 


3d   Lumbak 
nerve. 


4th  Lumdak 
nerve. 


(  Filaments  to  erector  spinae  muscle, 
I   Filaments   to  the  inter-transversales 
^       muscles, 

I   Filaments  to  integument  of  back  part 

[      of  gluteal  region. 

Filaments  to  multifidus  spina?  muscle, 

Filaments  to  integument  near  spinal 

column. 

['  Ilio-hypogastric  nerve,  ^  Given  off  by 


Lumbar 
Plexus. 


Ilio-inguinal  nerve, 
Communicating  to  2d 

lumbar. 
Genito-crural  nerve, 
External   cutaneous 

nerve. 
Communicating  to  3d 

lumbar.  J 

Part  of  anterior  crural  ^ 

nerve, 
Part   of   obturator        | 

nerve,  ! 

Part  of   accessory  ob-  f 

turator  nerve. 
Communicating  to  4lh 

lumbar. 
Part  of  anterior  crural 

nerve, 
Part   of    obturator 

nerve, 
Part  of   accessory  ob 

turator  nerve,  | 

Lumbo-sacral  cord.        J 


the  1st 

LUMBAR 
NERVE. 

Given  off  by 
the  2d 

LUMBAR 
NERVE. 


Given  off  by 
the  3d 

LUMBAR 
NERVE. 


Given  off  by 
the  4th 

^        LUMBAR 
NERVE. 


It  will  be  perceived  that  three  most  important  nerves,  viz., 
the  anterior  crural,  the  obturator,  and  accessory  obturator 
nerves,  are  formed  by  branches  both  of  the  third  and  fourth 
lumbar  nerves,  and  therefore  may  be  said  to  arise  by  two 
heads.  The  accessory  obturator  nerve,  however,  arises  occa- 
sionally by  a  branch  derived  only  from  the  fourth  lumbar 
nerve,  its  other  head  being  a  branch  given  off  from  the  obtu- 
rator nerve. 

The  second  table,  to  which  I  now  call  your  attention,  is 
constructed  to  show  the  distribution  of  each  of  the  seven 
large  branches  of  the  lumbar  plexus.  This  table  may  aid  in 
refreshing  your  memories  while  following  the  subsequent 
lectures,  while  it  also  gives  you,  at  a  glance,  a  better  concep- 
tion of  the  arrangement  of  any  special  nerve  than  a  mere 
verbal  description. 

^  Taken  from  "  The  Essentials  of  Anatomy "  (Darling  and  Panney).     New   York : 
G.  P.  Putnam's  Sons,  ICSO. 
30 


438 


THE  SPmAL  NERVES. 


TABLE  OF  THE   DISTRIBUTION  OF  THE   BRANCHES  OF  THE  LUMBAR   PLEXUS.» 

Iliac  branch.    ■{  Inte(jument  of  gluteal  region. 

yPy^   '  \       -j  Integument  of  the  hypogastric  region. 

Internal  oblique  muscle, 

Integument  of  upper  and  inner  portion  of  thigh, 

Integument  of  scrotum, 

Integument  of  penis, 

Integument  of  labium. 

Crcrnaster  muscle, 

Scrotum, 


f  (1)  Ilio-hypo-  _ 

I  GASTRIC. 


(2)  Ilio-ix- 

GUINAL. 


Lumbar 

PLEXUS. 


(3)  Genito- 

CRURAL. 


(4)  External 
cutaneous. 


Genital 

branch. 


Crural  branch 

Anterior 

branch. 
Posterior 

branch. 


'  Anterior 

division.  ■< 


(5)  Anterior 

CRURAL. 


Internal  cuta- 
neous nave 


Posterior 

division. 


(6)  Obtura- 
tor NERVE. 


(7)  Accessory 

NERVE  .      .      , 


Anterior 

branch. 


Posterior 

branch. 


Obturator 


Round  ligament  of  female. 
Iniegument  of  the  front  and  upper  portion 
of  the  thigh. 
\  Integ}iment  on  the  anterior  and  outer  as- 
)       pect  of  thigh,  as  low  as  the  knee. 
j  Integument  of  the  posterior  and  outer  as- 
{       pect  of  the  thigh. 

fThe  sartorius  muscle. 
Middle  cuia-   J  Integwiicnt  of  anterior  as- 
neous  nerve.  \      spect  of  thigh,  as  low  as 
the  knee. 

(Integument  of 
External  J      inner     and 
branch.    |      outer   sides 
(^     of  knee. 
(Integument  of 
Posterior  J      inner    sides 
branch,    j      of  the  thigh 
(^     and  the  kg. 
Long  or  intci'-  (  Integument  of  knee  joint 
nal     saphe-  ■<      and    front    and    inner 
nous  nerve.    (      sides  of  the  leg  and  foot, 
f  fAU  the  muscles  on  front 

of  thigh  except  the  ten- 
sor vagince  femoris  and 
the  sartorius. 
Two  in  number.  Distribu- 
ted to  capsule  of  knee 
joint,  and  probably  to 
the  hip  joint. 

^^''\tLhes.  [to /„>>,.. 

{To  gracilis. 
To  adductor  longus, 
To  pectineus, 
To  adductor  brevis. 
With   internal   cutaneous 

nerve. 
With  internal  saphenous 
(^     nerve. 

branches.]  To  >?n^^>"'^ 
Muscular  \  Obturator  extcrnus, 

branches,  j  Adductor  magnus. 
Muscular  j  ^^       ^ineus. 

branch.  (       '^ 
Articular  \  m„  i-^  j:^:^* 

branches.  jT*'^^^^^'"'^- 
Cutaneous         \  To    the    integument    of 

branches.  (      tliigh  and  leg. 


Mv^ailar 

branches. 


Articular 
branches. 


Anastomotic 
branches. 

Articular 


^  Taken  from  "  The  Essentials  of  Anatomy  "  (Darling  and  Ranney). 
P.  Putnam's  Sons,  18S0. 


Xew  York :   G. 


BRANCHES  OF  THE  LUMBAR  PLEXUS.  439 

THE   ILIO-HYPOGASTRIC    NERVE. 

This  nerve  is  named,  from  its  two  terminal  filaments  of 
distribution,  the  iliac  and  hypogastric  branch.  It  is  given  off 
by  the  first  lumbar  nerve  in  company  with  the  ilio-inguinal. 
It  emerges  from  the  outer  border  of  the  psoas  muscle,  crosses 
the  quadratus  lumborum,  then  perforates  the  transversalis 
muscle  of  the  abdomen,  and  finally  divides  between  it  and 
the  internal  oblique  muscle  into  its  iliac  and  hypogastric 
branches. 

The  iliac  hrancJi  pierces  the  internal  and  external  oblique 
muscles  just  above  the  crest  of  the  ilium,  and  supplies  the 
skin  of  the  gluteal  region,  while  the  hypogastric  branch 
pierces  the  internal  oblique  and  the  aponeurosis  of  the  ex- 
ternal oblique  muscle  a  little  above  the  external  abdominal 
ring,  and  supplies  the  skin  of  the  hypogastrium.  In  some 
cases  the  ilio-inguinal  nerve  is  incompletely  developed,  and 
this  nerve  may  then  be  traced  downward  to  the  skin  of  the 
penis,  scrotum,  labium,  and  thigh. 

THE   ILIO-IXGUIN^AL  KERVE. 

This  nerve  arises,  in  common  with  the  preceding  nerve, 
from  the  first  lumbar  nerve,  but  it  is  smaller  in  point  of  size 
than  its  fellow.  Like  the  ilio-hypogastric,  it  pierces  the  outer 
border  of  the  psoas,  and  crosses  the  quadratus  lumborum 
muscle,  lying  below  the  preceding  nerve  ;  it  then  pierces  the 
transversalis  muscle,  enters  the  inguinal  canal,  passes  through- 
out the  entire  length  of  that  canal  in  front  of  the  spermatic 
cord,  and  supplies  the  skin  of  the  penis,  scrotum,  labium, 
and  of  the  upper  and  inner  portions  of  the  thigh.  It  is  some- 
times incompletely  developed,  in  which  case  the  ilio-hypogas- 
tric nerve  takes  its  place. 

CLIIflCAL   POINTS   PERTAINING   TO   THE   ILIO-HYPOGASTRIC   AND   ILIO- 
INGUINAL    NERVES. 

These  two  nerves  are  sometimes  the  seat  of  a  severe  form 
of  neuralgia.     It  may  be  produced  by  disease  of  the  lumbar 


440  THE  SPINAL  NERVES. 

vertebrae,  structural  changes  in  the  parts  investing  the  lum- 
bar plexus,  pelvic  diseases,  exudations  in  the  substance  of 
the  psoas  muscle,  strains,  contusions,  exposure,  and  an  hys- 
terical condition.  The  pains  are  usually  of  a  paroxysmal 
character,  and  radiate  in  the  course  of  these  nerves  ;  they  are 
of  a  lancinating  type,  and  often  extremely  severe.  Painful 
points  may  be  detected  in  one  of  the  following  regions,  or 
possibly  in  all  of  them  :  1,  a  lumbar  point .^  near  the  spinous 
processes  of  the  lumbar  vertebrae  ;  2,  an  iliac  point,  near  to 
the  middle  of  the  crest  of  the  ilium,  where  the  ilio-hypogas- 
tric  nerve  pierces  the  transversalis  muscle  ;  3,  an  liypogastric 
pointy  slightly  above  the  external  ring,  where  the  ilio-hypo- 
gastric  nerve  pierces  the  aponeurosis  of  the  external  oblique 
muscle  ;  4,  an  inguinal  point ;  and  5,  points  upon  the  scrotum 
or  labium.  It  is  stated  by  ^N'otta '  that  this  type  of  neuralgia 
may  be  occasionally  accompanied  by  an  increase  in  the  sexual 
appetite,  and  a  spasmodic  contraction  of  the  cremaster  muscle. 

This  form  of  neuralgia  is  to  be  diagnosed  from  rheumatic 
myalgia  of  the  longissimus  dorsi  and  sacro-lumbalis  muscles, 
and  from  those  types  of  chronic  affections  of  the  uterus  which 
induce  pain  in  the  back.  It  might  also  be  possibly  mistaken 
for  an  attack  of  renal  or  biliary  colic.  The  diagnosis  will  be 
made  chiefly  by  the  ''puncta  dolorosa  " '  previously  described, 
by  the  course  of  the  pain,  and  by  its  intense  paroxysmal  and 
lancinating  character. 

The  nerves  which  are  distributed  to  the  skin  of  the  ab- 
dominal walls  may  be  considered  as  comprising  two  distinct 
sets,  based  on  the  physiological  action  of  the  abdominal  mus- 
cles which  are  supplied  by  them.  According  to  Hilton,  the 
abdomen  may  be  divided,  on  a  line  corresponding  with  the 
situation  of  the  umbilicus,  into  an  upper  or  respiratory  por- 
tion, and  a  lower  or  abdominal  portion.  The  uj^per  or  respi- 
ratory portion  is  supplied,  in  great  part,  by  the  lower  inter- 
costal nerves,  which  are  distributed  also  to  the  muscles  of  the 

'  As  quoted  by  Erb. 

'  A  name  applied  by  Valleix  to  the  spots  of  extreme  local  tcnderaess  found  along  the 
course  of  a  nerve  which  is  the  seat  of  neuralgia. 


THE  EXTERNAL    CUTANEOUS  NERVE.  44,1 

chest,  and  which,  if  taken  with  the  other  intercostal  nerves 
as  a  group,  are  essentially  respiratory  in  their  function.  The 
lower  or  abdominal  portion  of -the  abdomen  is  supplied  chiefly 
by  the  ilio-hypogastric  nerve,  although  the  ilio-inguinal,  the 
genito-crural,  and  the  posterior  branches  of  the  lumbar  nerves 
assist  in  furnishing  motor  power  to  the  muscles  of  that  region. 
The  subjacent  peritonaeum  is  unquestionably  supplied  from 
the  same  sources  of  nerve  power  as  the  muscles  and  skin  of 
the  individual  regions  of  the  abdomen,  and  it  is  considered 
probable  by  the  author  above  quoted  that  the  spinal  nerves 
which  are  distributed  to  the  skin,  muscles,  and  parietal  peri- 
tonaeum may  be  also  associated  with  the  visceral  layer  under- 
neath, by  means  of  communications  with  the  sympathetic 
nerve.  The  abdominal  muscles  unquestionably  assist  the  co- 
lon in  its  endeavors  to  force  the  faeces,  by  its  peristaltic  action 
alone,  throughout  its  length,  since  the  force  of  gravity  has 
to  be  overcome  in  its  ascending  portion,  and  the  curves  of  the 
sigmoid  flexure  in  its  terminal  portion.  It  would  therefore 
be  an  additional  confirmation  of  a  general  law  of  nerve  dis- 
tribution, provided  the  distribution  of  the  abdominal  nerves 
to  the  intestinal  covering  of  peritonaeum  could  be  fully  veri- 
fied ;  since  the  structures  which  assist  in  moving  the  adjacent 
organs — the  abdominal  muscles — would  be  supplied  from  the 
same  source  as  the  parts  moved,  as  well  as  the  skin  over  those 
muscles. 

THE  EXTERN-AL  CUTANEOUS  NERVE. 

This  nerve  arises  from  the  trunk  of  the  second  lumbar 
nerve,  in  common  with  the  genito-crural,  but  it  usually  re- 
ceives a  few  filaments  from  the  third  lumbar.  It  pierces  the 
psoas  muscle,  near  to  its  central  point,  and  crosses  the  iliacus 
muscle  in  order  to  reach  a  notch  below  the  anterior  superior 
spine  of  the  iliam,  where  it  escapes  below  Poupart' s  ligament. 

The  anterior  branch  of  this  nerve  pierces  the  fascia  lata  at 
about  four  inches  below  Poupart' s  ligament,  and  supplies  the 
integument  of  the  anterior  and  outer  aspects  of  the  thigh, 
while  the  posterior  branch  supplies  the  integument  of  the 
outer  and  posterior  aspects  of  the  same  region.    Both  of  these 


442 


THE  SPINAL  NERVES. 


terminal  branches  are  given  off  after  the  main  nerve  trunk  has 
escaped  from  beneath  Poupart's  ligament.  It  will  be  observed 
that  this  nerve  pierces  the  psoas  muscle  in  a  different  direc- 


Fig.  163. — The  cutatieous  nerves  of  the  thigh.     (Ilirschfeld.) 

1,  lumbar  and  sacral  portions  of  the  great  sympathetic;  2,  twelfth  dorsal  pair;  3,  first 
lumbar  pair;  4,  4',  ilio-hypogastric  branch;  5,  5',  ilio-inguinal  branch;  G,  second 
lumbar  pair ;  7,  origin  of  the  genito-crural  branch  ;  7',  this  same  branch  appearing 
and  descending  in  front  of  the  psoas  muscle ;  8,  origin  of  the  external  cutaneous 
nerve ;  8',  tlTis  same  branch  leaving  the  border  of  the  psoas,  and  dividing  at  the 
level  of  the  fold  of  the  groin ;  9,  third  lumbar  pair  ;  10,  fourth  lumbar  pair  ;^1 1,  fifth 
lumbar  pair;  12,  lumbo-sacral  trunk  ;  13,  gluteal  branch  of  the  iliohypogastric ;  14, 
its  abdominal  branch;  15,  its  genital  branches;  16,  external  cutaneous  nerve  passing 
under  Poupart's  ligament,  between  the  anterior  superior  and  inferior  spines  of  the 
ilium ;  17,  17, 17,  divisions  of  this  branch  ;  17',  point  of  origin  of  these  divisions  ;  18, 
18',  genital  branch  of  the  genito-crural  nerve;  19,  19,  femoral  division  of  this  nerve 
piercing  the  fascia  lata  in  the  neighborhood  of  the  saphenous  opening;  19',  this 
division  exposed  at  the  fold  of  the  groin,  to  show  its  relations  with  the  femoral  aitcry 
and  the  saphenous  vein  ;  20,  20',  anterior  crural  nerve  ;  21,  21",  obturator  nerve. 


tion  from  the  two  preceding  nerves,  and  that  it  crosses  over 
the  iliacus  muscle,  while  the  two  preceding  nerves  crossed  the 


THE   GENITO-CEURAL   NERVE,  443 

• 
quadratus  lumborum.     This  fact,  wMcli  is  true  also  of  tlie 

genito-crural  nerve,  is  to  be  remembered  in  tracing  the  seat  of 
origin  of  a  pain  felt  in  the  regions  supplied  by  either  of  these 
nerves.  We  would  naturally  look,  as  we  pass  toward  the 
trunk,  either  to  find  the  cause  of  such  a  pain  (manifested  by 
the  external  cutaneous  nerve)  in  the  region  of  Poupart'  s  liga- 
ment, or  to  detect  some  pelvic  cause  involving  the  iliacus 
muscle,  some  abnormal  condition  of  the  psoas  muscle,  or  some 
lesion  of  the  vertebrse  in  the  lumbar  region. 

THE    GEXITO-CRURAL    NERVE. 

This  nerve  arises,  in  common  with  the  external  cutaneous, 
from  the  second  lumbar  nerve,  although  it  occasionally  receives 
some  filaments  from  the  first  lumbar.  It  pierces  the  psoas 
muscle,  and  divides  into  its  two  terminal  branches  upon  its 
anterior  surface. 

The  genital  branch  crosses  the  external  iliac  artery  and 
passes  through  the  inguinal  canal  to  supply  the  cremaster 
muscle  and  the  scrotum  or  labium ;  it  lies  behind  the  sper- 
matic cord  in  the  male  and  the  round  ligament  in  the  female. 

The  crural  hrancli  pierces  the  fascia  lata  (after  escaping 
beneath  Poupart's  ligament  on  the  inner  side  of  the  psoas 
muscle)  on  the  outer  side  of  the  femoral  vessels,  and  supplies 
the  skin  of  the  upper  and  anterior  part  of  the  thigh,  anasto- 
mosing with  the  middle  cutaneous  branch  of  the  anterior 
crural  nerve. 

CLIN'ICAL    POINTS    PERTAINING   TO    THE    EXTERNAL    CUTANEOUS    AND 
GENITO-CRURAL  NERVES. 

As  both  of  these  nerves  are  distributed  chiefly  to  the  integ- 
nment,  a  knowledge  of  their  anatomy  affords  the  intelligent 
practitioner  a  means  of  tracing  the  situation  of  any  local  cause 
of  a  pain,  confined  to  the  regions  which  these  nerves  supply. 
While  their  course  is  snch  as  to  render  them  less  liable  to 
local  pressure  or  injury  than  the  obturator  or  anterior  crural 
nerves,  and  while  the  fact  that  they  are  distributed  to  no 
muscles  (excepting  the  cremaster)  deprives  them  of  much  of 


444  THE  SPmAL  NERVES. 

• 

the  physiological  interest  which  other  nerves  possess,  still  it 

is  possible  to  imagine  certain  localized  conditions  of  the  psoas 

and  iliacus  muscles,  local  swellings  in  the  vicinity  of  Pou- 

part's  ligament,  and  possible  forms  of  vertebral  disease  w^hich 

might  be  manifested  exclusively  through  the  medium  of  these 

nerves. 

THE  ANTERIOR  CRURAL  KERVE. 

This  is  the  largest  branch  of  the  lumbar  plexus.  It  arises 
mainly  from  the  third  and  fourth  lumbar  nerves,  but  often 
receives  a  fasciculus  from  the  second.  In  its  course,  it  per- 
forates the  psoas  muscle,  emerging  from  it  at  the  lower  part 
of  its  outer  border.  It  then  passes  between  the  psoas  and 
iliacus  muscles,  and  enters  the  thigh  by  escaping  under  Pou- 
part's  ligament  about  one  half  inch  to  the  outer  side  of  the 
femoral  artery.  Its  main  divisions  (the  middle  and  internal 
cutaneous  and  long  saphenous  nerves)  are  given  off  after  it 
enters  the  thigh.  The  distribution  of  each  of  these  terminal 
branches  is  shown  you  upon  the  table,'  but  I  would  call  your 
attention  to  some  points  of  special  interest  pertaining  to  the 
anterior  crural  nerve,  whic^h  will  perhaps  enable  you  to  ap- 
preciate the  value  which  some  portions  of  this  table  pos- 
sess. 

The  anterior  crural  nerve  supplies  nearly  all  of  those  mus- 
cles which  are  employed  in  the  first  effort  of  progression. 
As  the  act  of  taking  a  step  forward  is  performed,  we  flex  the 
thigh  upon  the  pelvis,  we  extend  the  leg  at  the  knee,  and  we 
slightly  evert  the  foot.'  Now,  all  the  muscles  which  aid  us 
in  performing  these  various  movements — the  psoas  and  ilia- 
cus, the  pectineus  and  sartorius,  the  four  muscles  of  the 
quadriceps  extensor,  and  the  subcrureus — are  supplied  by  the 
anterior  crural  nerve.  This  nerve  also  sends  branches  both  to 
the  knee  joint  and  hip  joint ;  the  capsular  ligament  of  the 
former,  as  well  as  that  of  the  latter,'  being  supplied  by  fila- 
ments which  can  easily  be  demonstrated  by  dissection.     If  we 

'  See  page  438  of  this  volume.  '  John  Hilton,  op.  cit. 

2  This  fact  is  not  so  stated  by  all  of  the  text-books  upon  descriptive  anatomy,  but, 
nevertheless,  I  regard  it  as  capable  of  demonstration. 


THE  ANTERIOR   CRURAL  NERVE. 


445 


now  consider,  in  the  third  place,  that  the  cutaneous  branches 
of  this  nerve  supply  the  skin  of  the  thigh,  and  also  the  re- 
gions over  the  two  joints  mentioned,  we  are  enabled  to  a2:ain 


Fig.   1G4. —  The  mvscuhr  branches  of  the  anterior  and  internal  portions  of  the  thigh. 

(Sappcy.) 

1,  anterior  crural  nerve  ;  2,  branch  which  it  furnishes  to  the  iliacus  muscle  ;  3,  twig  which 
it  sends  to  the  internal  portion  of  the  psoas  muscle  :  4,  middle  cutaneous  branch  of 
the  anterior  crural,  whose  three  branches  have  been  divided  close  to  their  origin  in 
order  to  show  the  branches  to  the  quadriceps  extensor  and  the  internal  saphenous 
nerve,  which  are  more  deeply  placed  ;  5  and  6,  muscular  filaments  of  the  internal 
cutaneous  nerve  ;  7,  origin  of  the  cutaneous  branches  which  pierce  the  fascia  lata  at 
the  level  of  the  saphenous  opening  ;  8,  deep  or  anastomotic  filament  of  the  internal 
cutaneous  branch  of  the  anterior  crural ;  9,  branches  to  the  rectus  muscle  ;  10, 
branches  to  the  vastus  externus  ;  11,  branches  to  the  vastus  internus;  12,  12,  inter- 
nal saphenous  nerve;  13,  patellar  branch  of  this  nerve;  14,  its  vertical  or  tibial 
branch  ;  15,  obturator  nerve  ;  16,  branch  which  it  furnishes  to  the  adductor  longus ; 
17,  branch  to  the  adductor  brevis ;  18,  branch  to  the  gracilis  ;  19,  branch  to  the  ad- 
ductor magnus  ;  20,  lumbo-sacral  trunk  ;  21,  junction  of  this  nerve  with  the  first 
sacral  nerve  ;  22,  22,  lumbar  and  sacral  portions  of  the  sympathetic ;  23,  external 
cutaneous  nerve. 


446 


THE  SPINAL  NERVES. 


I'/ 11 


i  \ 


\     7 


10 


1\ 


13 


12  '' 


14r 

Fig.  165. — A  diaqram  of  the  cuiancous  supply  of  the  anterior  aspect  of  the  lower  extirmiti/. 

1,  region  supplied  by  the  lateral  branches  of  the  intercostal  nerves;  2,  region  sup])lied  by 
the  anterior  branches  of  the  intercostal  nerves;  3,  region  supplied  by  the  ilio-hyix) 
gastric  nerve;  4,  region  supplied  by  the  ilio-inguinal  nerve;  5.  region  supplied  by 
the  genito-crural  nerve ;  G,  region  supplied  by  the  middle  cutaneous  branch  of  the 
anterior  crural  nerve ;  Y,  region  supplied  by  the  internal  cutaneous  branch  of  the 
anterior  crural  nerve  and  partly  by  the  obturator  nerve ;  8,  region  supplied  by  the 
external  cutaneous  nerve ;  9,  region  supjjlied  by  the  long  saphenous  branch  of  the 
anterior  crural  nerve  ;  10,  region  supplied  by  the  branches  of  the  external  popliteal 
nerve;  11,  region  supplied  by  the  musculo  cutaneous  nerve  ;  12,  region  supplied  by 
the  terminal  filaments  of  the  musculo-cutaneous  nerve;  13,  region  supplied  by  the 
external  saphenous  nerve  ;  14,  region  supplied  by  the  anterior  tibial  nerve. 


CLINICAL  POINTS  OB'  ANTERIOR   CRURAL  NERVE.     447 

record  a  confirmation  of  that  axiom  of  Hilton/  that  a  nerve 
which  supplies  a  joint  must  supply  also  muscles  which  move 
that  joint,  and  the  skin  over  the  insertion  of  those  muscles. 
The  long  saphenous  nerve  seems,  at  first  sight,  to  extend  far 
beyond  the  limits  of  the  muscular  distribution  of  the  anterior 
crural,  but,  when  we  look  closely  into  the  anatomical  rela- 
tions of  the  fascia  of  the  leg,  we  find  that  the  muscles  sup- 
plied by  the  anterior  crural  nerve  are  attached  to  it,  especially 
the  sartorius,  whose  insertion  into  this  fascia  is  as  intimate 
as  that  of  the  biceps  into  the  fascia  of  the  forearm  ;  and 
we  also  notice  that  the  cutaneous  distribution  over  this 
fascia  is  derived  from  the  same  sources  as  are  the  muscles 
which  are  attached  to  it.  This  fact  is  in  perfect  accord  with 
the  axiom  given  in  a  previous  lecture,  viz.,  that  a  fascia,  to 
which  muscles  are  attached,  must  be  considered  as  one  of  the 
points  of  insertion  of  the  muscles  connected  with  it,  and  that 
the  cutaneous  distribution  over  such  a  fascia  will  be  found  to 
be  derived  from  the  nerves  which  supply  those  muscles.  We 
thus  discover  in  the  lower  extremity  the  same  general  laws 
of  nerve  distribution,  as  were  verified  in  connection  with  the 
upper  extremity,  fully  carried  out ;  and  it  is  thus  that  many 
of  the  apparent  deviations  from  the  natural  order  of  nerve 
supply  may  be  explained  by,  and  often  act  as  guides  to,  the 
presence  of  some  anatomical  fact,  whose  physiological  impor- 
tance had  either  not  been  recognized  or  properly  appre- 
ciated. 

CLINICAL   POINTS   PERTAINING   TO   THE   ANTERIOK   CRURAL  NERVE. 

The  relation  of  this  nerve  to  the  femoral  artery  as  it  passes 
underneath  Poupart's  ligament  and  its  still  more  intimate  re- 
lation with  that  vessel  in  Scarpa's  space  render  it  of  special 
interest  to  the  surgeon.  Its  internal  cutaneous  branches 
cross  the  upper  part  of  the  femoral  artery  in  that  space,  be- 
fore it  becomes  properly  a  cutaneous  nerve ;  while  the  long 
saphenous  nerve  lies  to  the  outer  side  of  that  vessel  for  nearly 
its  entire  length,  being  at  first  slightly  removed  fromx  it,  but 

'  Op.  cit. 


448  THE  SPINAL  NERVES, 

approaching  it  more  closely  in  the  lower  part  of  its  course. 
This  latter  nerve  also  bears  an  intimate  relation  with  the  in- 
ternal saphenous  vein  for  the  greater  portion  of  its  course ; 
hence  the  pain  experienced  from  varicose  veins  in  this  region. ' 

It  is  customary  with  surgeons  to  regard  a  pain  which  is 
localized  at  the  iniier  side  of  the  knee  (since  the  obturator 
nerve  is  distributed  to  that  region)  as  strongly  diagnostic  of 
disease  of  the  hip  joint,  because  that  nerve  is  supposed  to  have 
an  intimate  connection  with  the  internal  structures  of  the  hip. 
So  strongly  is  this  impression  grounded  in  the  minds  of  some 
of  our  prominent  surgical  authors  that  the  presence  of  pain 
in  any  other  locality  than  that  just  mentioned  is  not  con- 
sidered as  particularly  indicative  of  morbus  coxarius ;  and 
the  inference  is  certainly  implied,  if  not  directly  stated,  that 
the  accuracy  of  diagnosis  of  this  condition  can  be  questioned 
if  this  symptom  be  not  confined  to  the  region  supplied  by  the 
obturator  nerve.  I  am  not  prepared  to* admit  that  pain  in  the 
knee  is  always  present  in  morbus  coxarius,  nor  am  I  inclined 
to  think  that  the  anterior  crural  nerve,  from  its  distribution 
to  the  capsular  ligament  of  the  hip  joint,  can  not  also  be  one 
of  the  sources  of  sympathetic  pains  referred  to  the  knee,  in 
case  the  hip  be  diseased.  I  admit  that  the  obturator  nerve, 
from  its  distribution  to  the  internal  structures  of  the  hip  joint,' 
is  the  most  frequent  source  of  transmission  of  these  sympa- 
thetic pains ;  but  the  sciatic  and  anterior  crural  nerves  may 
also  indicate  an  irritation  of  their  filaments  to  the  capsule  of 
the  hip  by  pains  referred  to  the  other  regions  which  they 
supply. 

Spasm  of  the  quadriceps  extensor  muscle,  which  is  sup- 
plied by  the  anterior  crural  nerve,  is  often  observed  in  artic- 
ular neuralgia  of  the  knee  joint ;  >vhile  the  rigid  extension 
of  the  leg  upon  the  thigh,  met  with  in  tetanus,  is  dependent 
upon  irritation  of  this  nerve.     In  his  treatise  upon  nervous 

'  Varicose  veins  are  most  common  on  the  inner  side  of  the  leg.  The  pain  of  these 
tumors  may  often  be  arrested  by  simple  elevation  of  the  foot,  since  the  excess  of  blood 
in  the  part  is  thus  relieved. 

'  It  is  claimed  by  Hilton  that  this  nerve  is  distributed  chiefly  to  the  ligamentum  teres, 
and  that  this  accounts  for  it  being  so  frequently  affected  by  disease  of  the  hip  joint. 


PARALYSIS  OF  ANTERIOR   CRURAL  NERVE. 


449 


diseases,  Eulenberg  reports  a  case  of 
clonic  spasm  localized  in  the  quadri- 
ceps extensor  muscle  whicli  was  in- 
duced whenever  an  attempt  to  walk 
I  or  stand  was  made,  but  such  cases  are 
pf  rare  occurrence. 
I  Paralysis  confined  to  the  anterior 
pural  nerve  is  not  of  common  occur- 
rence, but  is  still  observed  as  a  result 
of  injuries  to  the  vertebral  column  and 
pelvis,  from  tumors  and  extravasa- 
tions of  blood  in  the  region  of  the 
Cauda  equina,  and  as  a  sequel  to  a 
severe  type  of  inflammation  of  the 
knee  Joint.  It  has  been  known  to  oc- 
cur in  connection  with  psoas  abscess 
and  simple  inflammation  of  the  psoas 
muscle ;  while  fractures  of  the  thigh, 
cuts,  stab  wounds,  neuritis,  pelvic  tu- 
mors, and  tumors  of  the  thigh,  have 
been  reported  as  inducing  this  type  of 
paralysis.  Finally,  it  is  a  frequent 
symptom  of  spinal  paralysis  in  all  of 
its  forms,  and,  more  rarely,  of  cere- 
bral paralysis  and  of  progressive  mus- 
cular atrophy. 

From  what  has  been  already  said 
as  to  the  distribution  of  this  nerve  to 
muscles,  it  is  easy  to  understand  that 
the  symptoms  of  this  type  of  paralysis 
will  be  confined  to  the  inability  of  the 
anterior  thigh  muscles  to  perform 
their  accustomed  functions.  Such  pa- 
tients can  not  flex  the  leg  at  the  hip 
joint  or  raise  the  body  from  the  re- 
cumbent position ;  neither  are  they 
able  to  extend  it  nor  to  move  the  leg 


Fig.  166. — Cutaneous  verves  of 
the  antei'ior  part  of  the 
tldgh.     (Sappey.) 

1,  external  cutaneous  branch  of 
the  lumbar  plexus  ;  2,  2, 
external  cutaneous  or  su- 
perior perforating  branch  of 
the  anterior  crural  nerve  ; 
3,  3,  middle  cutaneous  or 
inferior  perforating  branch 
of  this  nerve;  4,  filament 
furnished  by  this  branch 
to  the  scrotum  ;  5,  internal 
cutaneous  branch  of  the 
anterior  crural  nerve ;  G, 
superficial  division  of  this 
branch  ;  V,  deep  division  of 
the  same  ;  8,  superficial  di- 
vision of  the  small  musculo- 
cutaneous branch  of  the  an- 
terior crural ;  9,  transverse 
or  patellar  branch  of  the 
internal  saphenous  nerve ; 
10,  internal,  vertical,  or  tib- 
ial branch  of  the  same. 


450  THE  SPINAL  NERVES. 

and  foot  forward  when  sitting.  For  this  reason  standing  and 
walking  are  rendered  very  insecure,  and  such  acts  as  running, 
jumping,  etc.,  are  often  impossible  with  patients  so  afflicted. 
The  regions  of  the  skin  which  are  supplied  by  the  anterior  cru- 
ral nerve  may  manifest  disturbances  of  sensibility.  If  the  scro- 
tum, labium,  hypogastrium,  or  inguinal  regions  exhibit  the 
same  disturbances  of  sensibility,  the  seat  of  the  paralysis  is 
positively  indicated  as  being  above  the  origin  of  the  branches 
of  the  two  upper  lumbar  nerves  (ilio-hypogastric,  ilio-ingui- 
nal,  genito-crural,  and  external  cutaneous  nerves).  Among 
the  evidences  of  disturbed  sensibility  which  you  may  be  called 
upon  to  recognize  may  be  mentioned  the  conditions  of  anaes- 
thesia, hypersesthesia,  the  sensations  of  furriness,  numbness, 
and  chilliness. 

Atrophy  of  the  muscles  supjjlied  by  the  anterior  crural 
nerve  may  follow  such  paralysis.  This  is  generally  so  well 
defined  as  to  be  apparent  to  the  naked  eye  when  the  two 
thighs  are  compared  ;  but  it  may,  occasionally,  be  so  slight  as 
to  require  careful  measurement  of  the  thighs.  In  some  cases, 
certain  muscles  exhibit  this  atrophy  more  than  others  of  the 
group,  and  even  parts  of  muscles  may  appear  flaccid,  relaxed, 
and  shrunken,  while  others  preserve  their  normal  appearance. 

Crural  neuralgia  may  be  manifested  by  paroxysms  of 
pain  upon  the  anterior  and  inner  surfaces  of  the  thigh  and 
leg.  It  may  affect  the  inner  border  of  the  dorsal  surface  of 
the  foot  and  large  toe.  It  is  less  frequent  than  neuralgia  ol 
the  sciatic  nerve,  which  affects  the  back  of  the  leg  and  plantar 
region  of  the  foot.  This  diseased  condition  may  result  from 
compression  of  the  lumbar  plexus,  from  degeneration  of  neigh- 
boring lymphatic  glands,  exudations  upon  or  in  the  substance 
of  the  psoas  muscle,  aneurism  of  the  iliac  arteries,  strangu- 
lated hernia  of  the  femoral  region,  dislocations  at  the  hip 
joint,  traumatism,  exposure  to  cold  or  dampness,  coxalgia, 
etc.  The  diagnostic  points  of  tenderness  are  detected  as  fol- 
lows :  1,  a  crural  point,  at  the  exit  of  the  nerve  below  Pou- 
part's  ligament ;  2,  an  anterior  femoral  imint^  at  the  place 
of  exit  of  the  saphenous  nerve  through  the  fascia  lata  ;  3,  an 


CUTANEOUS  NERVES   OF  LOWER  EXTREMITY.          451 


%     15 


16 


19 


\  17  \ 


20 


21   i 


I   zz 


23, 


2^ 


25 


.  1 OY. — A  diagram  of  the  cutaneous  supply  of  the  posterior  aspect  of  the  Icwer  extremities. 

region  supplied  by  the  lateral  branches  of  the  intercostal  nerves ;  1 6,  region  supplied 
by  the  posterior  branches  of  the  lumbar  nerves;  17,  region  supplied  by  the  iliac 
branch  of  the  iliohypogastric  nerve;  18,  region  supplied  by  the  pudic  nerve;  19, 
region  supplied  by  the  inferior  gluteal  branch  of  the  small  sciatic  nerve ;  20,  region 
supplied  by  the  external  cutaneous  nerve ;  21,  region  supplied  by  the  internal  cuta- 
neous branch  of  the  anterior  crural  nerve  ;  22,  region  supplied  by  the  small  and 
great  sciatic  nerves  ;  2^,  region  supplied  by  branches  from  the  external  popliteal 
nerve ;  24,  region  supplied  by  the  external  saphenous  nerve  ;  25,  region  supplied  by 
the  posterior  tibial  nerve. 


452  TEE  SPINAL  NERVES, 

articular  point,  at  the  inner  side  of  the  knee  joint,  where 
the  nerve  divides ;  4,  a  plantar  pointy  on  the  inner  side  of 
the  foot ;  and,  finally,  5,  a  digital  p>oint^  over  the  tuberosity 
of  the  big  toe. 

Spasm  of  the  muscles  of  the  hip,  supplied  by  the  anterior 
crural  nerve  (the  spasmodic  contracture  of  Stromeyer),  may 
occur  from  any  of  the  causes  of  crural  paralysis  previously 
mentioned.  The  thigh  is  then  flexed,  the  pelvis  raised  up  on 
the  affected  side,  and  the  limb  shortened  and  made  rigid. 

THE   OBTURATOR   NERVE. 

This  nerve  arises  mainly  from  the  third  and  fourth  lumbar 
nerves,  but  it  often  receives  a  fasciculus  from  the  second.  It 
descends  in  the  innermost  fibers  of  the  psoas  muscle,  as  far  as 
the  level  of  the  brim  of  the  pelvis,  when  it  escapes  from  the 
inner  border  of  that  muscle,  crosses  the  sacro-iliac  articula- 
tion, accompanies  the  obturator  vessels  along  the  outer  wall 
of  the  pelvis  lying  slightly  above  them,  and  passes  into  the 
thigh  through  the  upper  part  of  the  obturator  foramen. 

The  table,'  previously  referred  to,  will  enable  you  to  grasp 
the  details  of  the  subdivisions  of  this  nerve,  and  the  distribu- 
tion of  each  branch  ;  but  it  fails  to  point  out  some  important 
facts  pertaining  to  this  nerve,  which  help  to  explain  its  physi- 
ological attributes  and  to  elucidate  its  clinical  bearings. 

In  the  first  place,  we  can  see  by  this  table  that  the  obtu- 
rator nerve  sends  filaments  to  the  hip  joint  and  the  knee 
joint.  To  the  former  articulation  two  filaments  of  this  nerve 
can  be  traced,  one  given  off  to  the  capsular  ligament,  as  the 
nerve  passes  through  the  obturator  foramen,  the  other  given 
off  to  the  ligament um  teres  in  the  region  of  the  notch  in  the 
acetabulum  ;  while,  in  the  case  of  the  knee  joint,  the  obturator 
nerve  sends  filaments  which  enter  that  articulation  at  its  pos- 
terior part,  and  which  are  probably  intimately  associated 
with  its  internal  structures.  The  close  relation  which  this 
nerve  bears  to  the  sacro-iliac  articulation  renders  it  probable 

'  Sec  page  438  of  this  volume. 


THE   OBTURATOR  NERVE. 


453 


that  some  small  filaments  from  the  obturator  nerve  could  be 
traced  to  this  joint,  although  anatomical  authors  do  not  men- 
tion this  fact  as  proven.    In  relation  to  this  point,  I  quote  from 


Fig.   1G8. —  The  muscular  branches  of  the  anterior  and  internal  portions  of  the  thigh. 

(Sappey.) 

1,  anterior  crural  nerve  ;  2,  branch  which  it  furnishes  to  the  iliacus  muscle  ;  3,  twig  which 
it  sends  to  the  internal  portion  of  the  psoas  muscle  :  4,  middle  cutaneous  branch  of 
the  anterior  crural,  whose  three  branches  have  been  divided  close  to  their  origin  in 
order  to  show  the  branches  to  the  quadriceps  extensor  and  the  internal  saphenous 
nerve,  which  are  more  deeply  placed  ;  5  and  6,  muscular  filaments  of  the  internal 
cutaneous  nerve  ;  7,  origin  of  the  cutaneous  branches  which  pierce  the  fascia  lata  at 
the  level  of  the  saphenous  opening  ;  8,  deep  or  anastomotic  filament  of  the  internal 
cutaneous  branch  of  the  anterior  crural ;  9,  branches  to  the  rectus  muscle ;  10, 
branches  to  the  vastus  externus  ;  11,  branches  to  the  vastus  internus;  12,  12,  inter- 
nal saphenous  nerve;  13,  patellar  branch  of  this  nerve;  14,  its  vertical  or  tibial 
branch  ;  15,  obturator  nerve  ;  16,  branch  which  it  furnishes  to  the  adductor  longus ; 
17,  branch  to  the  adductor  brevis;  18,  branch  to  the  gracilis  ;  19,  branch  to  the  ad- 
ductor magnus  ;  20,  lumbo-sacral  trunk  ;  21,  junction  of  this  nerve  with  the  first 
sacral  nerve ;  22,  22,  lumbar  and  sacral  portions  of  the  sympathetic ;  23,  external 
cutaneous  nerve. 
31 


454  THE  SPIXAL  NERVES. 

the  most  excellent  inonograx)li  of  Hilton'  as  follows :  ^'I  am 
disposed  to  think  it  sends  some  filaments  to  that  articulation, 
or,  at  any  rate,  it  lies  close  to  it  and  would  be  likely  to  suffer 
from  its  proximity  to  it  when  diseased."  Now,  this  distribu- 
tion to  the  internal  portions  of  two  joints,  and  possibly  to  a 
third,  is  the  best  possible  explanation  of  the  fact  that  the  ob- 
turator nerve  is  the  most  frequent  source  of  transmission  of 
sympathetic  pains,  in  case  the  hip  joint  be  the  seat  of  the 
disease,  since  the  situation  of  its  filaments  causes  it  to  per- 
ceive the  first  inflammatory  changes  within  the  hip  ;  and  the 
effects  of  this  irritation  are  naturally  manifested  in  its  termi- 
nal filaments — in  the  knee  joint  and  the  skin  upon  the  inner 
side  of  that  articulation. 

When  we  consider  the  course  of  the  obturator  nerve  more 
in  detail,  w^e  will  perceive  tlxnXpain  in  the  region  of  the  Jcnee 
may  be  due  to  other  causes  than  morbus  coxarius.  It  may 
be  the  external  evidence  of  disease  of  the  third  or  fourth  lum- 
bar vertebrse,  of  disease  of  the  sacro-iliac  articulation,  of  a 
psoas  abscess  pressing  upon  it,  and,  if  the  pain  be  confined  to 
the  left  side,  a  distention  of  the  sigmoid  flexure  of  the  colon 
by  faeces,  or  a  malignant  tumor  of  that  portion  of  the  colon 
or  of  the  rectum  might  create  pain  in  this  region.  It  is  well, 
therefore,  when  a  patient  suffering  from  a  pain  localized  upon 
the  inner  aspect  of  the  knee  joint  is  brought  to  you,  to  care- 
fully examine  all  the  different  portions  of  the  course  of  Ww 
obturator,  anterior  crural,  and  sciatic  nerves  before  you  de- 
cide as  to  the  exciting  cause  of  the  pain,  remembering  always 
that  pain  can  be  perceived  through  no  other  structures  than 
the  nerves  which  are  distributed  to  the  region  where  the  pain 
is  felt,  and  that,  by  following  the  course  of  the  nerve  suffer- 
ing from  irritation,  the  seat  of  the  disease  to  which  the  pain 
is  due  may  be  confidently  sought  for. 

The  distribution  of  the  obturator  nerve  affords  us  somr 
lessons  as  to  the  physiological  groupings  of  the  muscles  w^hich 
act  upon  the  thigh  and  leg.  It  first  supplies  the  obturator 
extemus,  and  then  the  adductor  brevis,  the  adductor  longus. 

1  Op,  cit. 


» 


DISTRIBUTION  OF  THE  OBTURATOR  NERVE.  455 

the  adductor  magnus,  and  the  gracilis.  In  some  cases  the 
pectineus  is  supplied  by  this  nerve  or  the  accessory  obturator 
nerve,  but  its  chief  source  of  supply  is  undoubtedly  from  the 
anterior  crural.  This  fact  would  seem  to  indicate  that  the 
gracilis  muscle,  whose  supply  from  the  obturator  nerve  is 
very  constant,  should  be  classed  as  an  adductor  muscle,  rather 
than  as  a  flexor,  and  that  this  is  its  true  action  seems  well 
proven  on  mechanical  principles.  Its  point  of  insertion  is 
just  below  the  central  point  of  the  limb  which  it  moves,  hence, 
it  seizes  the  limb  just  beyond  the  central  point,  between  the 
fulcrum  (the  hip  joint)  and  the  resistance,  and  is  thus  able  to 
greatly  assist  the  adductor  muscles.  The  obturator  nerve  is 
thus,  physiologically  considered,  the  adductor  nerve  of  the 
lower  extremity,  while  the  muscles  which  it  supplies  also  act 
as  external  rotators  of  the  thigh,  on  account  of  the  obliquity 
of  their  fibers.  That  the  pectineus  muscle  acts  as  a  flexor  as 
well  as  an  adductor  is  proven  by  its  nerve  supply,  as  well  as 
by  the  direction  of  its  fibers  and  its  points  of  origin  and  in- 
sertion, since  it  receives  filaments  both  from  the  anterior  cru- 
ral and  obturator. 

CLINICAL   P0I:N^TS   PERTAINIls^G   TO  THE   OBTURATOR    NERVE. 

.  The  diagnostic  value  of  pain  in  the  region  of  the  knee 
joint  as  an  evidence  of  disease  in  other  localities,  to  which 
the  obturator  nerve  is  either  distributed  or  with  which  it 
bears  some  intimate  relations,  has  been  discussed  already  at 
some  length.'  Such  a  pain  may  be  dependent,  however,  also 
upon  lesions  interfering  with  the  free  action  of  the  anterior 
crural  and  sciatic  nerves,  and,  for  that  reason,  the  course  of 
these  three  nerves  should  always  be  carefully  examined  be- 
fore a  positive  diagnosis  can  be  made  as  to  the  exciting  cause 
of  pain  in  the  region  of  the  knee. 

The  obturator  nerve  is  even  less  frequently  affected  with 
isolated  paralysis  than  the  anterior  crural,  but,  if  so,  it  may 
be  referable  to  the  same  list  of  causes.  In  addition  to  the 
causes  mentioned,  may  be  added,  however,  compression  of  the 

^  See  page  448  of  this  volume. 


456  THE  SPmAL  NERVES, 

obturator  nerve  from  a  strangulated  hernia  through  the  obtu- 
rator foramen,  the  pressure  exerted  by  the  head  of  a  foetus 
during  its  passage  through  the  pelvis,  and  the  use  of  forceps 
during  difficult  labors. 

From  what  has  been  said  as  to  the  supply  of  muscles  by 
this  nerve,  it  is  apparent  that  a  patient  afflicted  with  obtu- 
rator paralysis  can  not  adduct  the  thigh,  or  perform  the  acts 
of  pressing  the  knees  tightly  together  or  of  crossing  the 
affected  leg  over  the  other.  Since  the  adductor  muscles  assist 
in  the  external  rotation  of  the  thigh,  this  movement  is  im- 
paired, especially  in  the  sitting  posture,  when  the  external 
rotators  attached  to  the  great  trochanter  are  rendered  inert. 
The  affected  leg  soon  becomes  fatigued  in  walking,  and  riding 
upon  horseback  is  difficult,  since  the  knees  can  not  grasp  the 
saddle.  Some  disturbances  of  sensibility  may  be  detected  in 
the  regions  of  the  sldn  supplied  by  this  nerve  ;  these  will  be 
the  same  in  character  as  those  mentioned  as  existing  in  crural 
paralysis.  * 

THE   ACCESSORY   OBTURATOR   NERVE. 

This  nerve  is  sometimes  wanting.  When  it  is  present,  its 
origin  is  extremely  variable.  It  may  arise  from  the  third  and 
fourth  lumbar  nerves ;  from  the  fourth  lumbar  and  obturator 
nerves  ;  or  by  separate  filaments  derived  from  the  second, 
third,  and  fourth  lumbar  nerves.  It  descends  along  the  inner 
side  of  the  psoas  muscle,  crosses  in  front  of  the  pubes,  passes 
behind  the  pectineus  muscle,  and  there  divides  into  branches 
to  the  pectineus  and  the  hip  joint.  It  usually  gives  off  a  large 
branch  of  communication  to  the  obturator  nerve  (which  is 
often  larger  than  the  continuation  of  the  accessory  nerve  it- 
self), and  terminates  as  a  cutaneous  nerve  to  the  thigh  and 
leg. 

The  frequent  absence  of  this  nerve  deprives  it  of  any  clin- 
ical importance,  as  it  is  impossible  in  any  one  case  to  decide 
if  pain  in  the  regions  supplied  by  the  obturator  nerve  is  partly 
due  to  the  accessory  obturator  or  not,  while  the  variations  in 

*  Sec  page  450  of  this  volume. 


THE  SACRAL  NERVES.  457 

the  method  of  origin  of  the  nerve  renders  it  impossible  to 
definitely  decide  as  to  the  seat  of  irritation,  provided  the 
pain  could  be  traced  to  the  accessory  nerve  and  localized 
above  the  pelvis. 


THE   SACRAL  NERVES. 

We  now  have  reached,  in  the  natural  progress  of  this 
course  of  lectures,  the  terminal  nerves  of  the  spinal  cord. 
As  was  the  case  with  those  of  the  lumbar  region,  the  sacral 
nerves  divide  into  anterior  and  posterior  divisions,  but  they 
differ  from  the  lumbar  nerves  in  the  fact  that  these  ante- 
rior and  posterior  divisions  escape  from  separate  foramina 
in  the  sacrum,  while,  in  the  portions  of  the  cord  above  the 
sacral  region,  the  spinal  nerves  divide  after  their  escape 
from  the  inter-vertebral  foramina.  These  nerves  form,  by 
their  anterior  divisions  and  the  addition  of  the  lumbo-sacral 
cord,  the  sacral  plexus  ;  while  their  posterior  divisions  are 
distributed  to  the  muscles  of  the  lower  lumbar  region  and 
to  the  integument  of  the  gluteal,  sacral,  and  coccygeal  re- 
gions. 

The  sacral  plexus  is  triangular  in  shape,  and  is  formed 
by  the  lumbo-sacral  cord,  the  three  upper  sacral  nerves 
(their  anterior  divisions),  and  a  portion  of  the  fourth  sa- 
cral nerve.  Its  constituent  fibers  converge  to  form  one  flat- 
tened cord,  which  leaves  the  pelvis  through  the  lower  part 
of  the  great  sacro-sciatic  foramen,  below  the  pyriformis 
muscle,  while,  within  the  pelvis,  the  plexus  lies  upon  the 
pyriformis  muscle,  and  is  covered  by  the  pelvic  fascia  and 
the  two  terminal  branches  of  the  anterior  division  of  the 
internal  iliac  artery  (the  sciatic  and  pudic).  The  branches 
which  are  given  off  by  this  plexus  are  arranged,  in  the 
table  which  I  now  show  you,  in  such  a  way  as  to- make 
them  apparent  to  the  eye,  while  the  distribution  of  each 
is  shoAvn  in  the  next  table  in  detail.  The  first  table  is 
not  intended  to  exhibit  alone  the  branches  of  the  sacral 
plexus,  but  rather  to  give  the  general  arrangement  of  the 


458 


THE  SPINAL  NERVES. 


sacral  nerves  in  their  entirety.  You  will  perceive  that 
the  arrangement  of  both  the  anterior  and  posterior  divis- 
ions is  considered,  and  that  the  component  parts  of  the 
sacral  plexus,  as  well  as  its  main  subdivisions,  are  clearly  set 
forth. 

NERVES   OF  THE  SACRAL   REGION.' 


SACRAL 
NERVES. 


'  Posterior 
divisions. 


External 

branches. 


Anterior 
divisions. 


'  Form  anastomotic  loops  on  the  back  part 
of  the  sacrum  and  on  the  posterior  aspect 
of  the  great  sacro-sciatic  ligament, 
Terminate   in   cutaneous  branches  in    the 
gluteal  region. 
[  Are  distributed   to  the   multifidus   spinas 
Internal  J       muscle, 

branches.  1  The  back  part  of  the  coccyx  is  supplied  by 
[      the  two  lower  nerves. 


f  LUMBO-SACRAL 

CORD. 

1st  sacral 

nerve. 

2d  sacral 

nerve. 

OD    SACRAL 

nerve. 

Part  of  4th  sa- 
cral nerve. 


.SACRAL    . 
r  PLEXUS.  ^ 


J 


(1)  Superior  gluteal  nerve, 

(2)  Muscular  branches, 

(3)  Small  sciatic  nerve, 

(4)  Great  sciatic  nerve, 

(5)  PuDic  nerve, 
[  (6)  Articular. 


Each  of  the  five  branches  of  the  sacral  plexus,  as  well  as 
those  included  in  the  muscular  group,  to  which  no  special 
names  are  given,  will  now  be  separately  described.  I  have 
endeavored  to  embrace  in  this  second  table  all  the  points 
pertaining  to  the  purely  anatomical  distribution  of  each 
of  these  nerves,  but  much  of  interest,  from  a  clinical  as- 
pect, still  remains  in  relation  to  some  of  them,  which  can 
not  be  shown  in  a  tabular  form.  This  table  will,  however, 
prove  of  assistance  to  you  in  reviewing  the  distribution  of 
the  nerve  which  is,  at  any  time,  under  discussion,  and,  fur- 
thermore, avoid  lengthy  descriptions  of  a  purely  anatomical 
character. 


'  Taken  from  the  "Essentials  of  Anatomy"  (Darling  and  Ranney).     G.  P.  Putnam's 
Sons,  New  York,  1880. 


THE  SUPERIOR   GLUTEAL  NERVE. 


459 


DISTRIBUTION   OF  THE   BRAI^CHES   OF   THE   SACRAL   PLEXUS. 


SACRAL 
PLEXUS. 


SCPERIOR 
GLUTEAL. 


JfuSCULAR 

branches. 


Articular 
branches. 


Small 

SCIATIC 


\  Superior  hv^xidx.  \  Gluteus  medius  muscle 

^  {  (jtluteus  minimus  muscle. 

\  I  Gluteus  medius  muscle, 

Inferior  branch.  4  Gluteus  minhnus  muscle, 

(  Tensor  vaginae  femoris. 
'  Pyriformis, 
Obturator  internus, 
Gemellus  superior, 
Gemellus  inferior, 
Quadratus  femoris. 

To  hip  joint. 

[  Lifer i or    cjluteal  i 


branch. 


dal  branch. 


Cutaneous 

branch. 


Articular  (to  the  hip  joint). 


Gluteus  maximus  muscle, 

/   Integument  of  the  side  of  the  penis  or  vidva. 

{  Integximent  of  perinaeum, 
?-  J   Integument  of  upper  and  inner  part  of  the 

I       thigh, 

y  Integument  of  scrotum  or  labium. 

\  Integument  over  the  gluteus 
{      maximus  muscle, 
i  Integument  of  the  inner  and 
-|      outer  sides  of  posterior 
(      aspect  of  the  thigh. 


Ascending. 


Descending. 


Great 

SCIATIC  ■{  Muscular 

NERVE. 


Terminal  . 


PuDir; 

NERVE. 


Adductor  magnus,  " 

Semi-membranosus, 

Semi-tendinosus, 

Biceps  flexor  cruris. 

External  popliteal  nerve, 

Lvternal  popliteal  nerve. 

Cutaneous  or  (  Integument  of  anal  region, 
superficial  -j  scrotum,  penis,  and  labia, 
perineal.      {  Sphincter  ani  muscle. 

^ruscular  .     .  ■{  Muscles  of  the  perinaeum. 
I  Inferior  hemorrhoidal. 

I  Dorsal  nerve  of  j   Integument  of  the  dorsum  of  the  penis, 
(^     penis.  I  Branch  to  corpora  cavernosa  of  the  penis. 


Perineal 


THE   SUPERIOR   GLUTEAL  NERVE. 

This  nerve  arises  from  the  back  part  of  the  lumbo-sacral 
cord,  and,  while  generally  included  as  a  branch  of  the  sacral 
plexus,  can  not  be,  therefore,  properly  regarded  as  a  nerve  of 
sacral  origin.  It  escapes  from  the  pelvis  through  the  upper 
part  of  the  great  sacro- sciatic  foramen,  in  company  with  the 
gluteal  vessels,  lying  above  the  pyriformis  muscle.  It  divides 
into  a  superior  and  an  inferior  branch,  as  is  shown  in  the 
table '  to  which  I  have  called  your  special  attention,  the  for- 
mer of  which  accompanies  the  superior  gluteal  artery  between 

'  Modified  from  a  table  taken  from  "  The  Essentials  of  Anatomy  "  (Darling  and  Ran- 
ney).       G.  P.  Putnam's  Son^  New  York,  1881. 
^  See  page  459  of  this  volume. 


460  TEE  SPIXAL  NERVES. 

the  gluteus  medius  and  minimus  muscles,  while  the  latter 
passes  between  the  same  muscles,  but  lower  than  its  fellow. 

The  distribution  of  this  nerve  to  the  gluteus  medius, 
gluteus  minimus,  and  tensor  vaginae  femoris  muscles,  stamps 
it  as  the  one  which  presides  chiefly  over  the  act  of  internal 
rotation  of  tJie  thigh,  since  these  three  muscles  are  the  only 
ones  which  can  perform  this  limited  movement  of  the  femur. 
Its  cutaneous  distribution  again  confirms  the  axioms  of  Hil- 
ton ; '  since  the  skin  over  these  muscles  is  thus  supplied,  while 
some  filaments  running  over  the  fascia  lata,  to  which  the 
tensor  vaginse  femoris  is  attached,  can  be  demonstrated. 

CLINICAL   POINTS   PERTAINING  TO   THE   SUPERIOR  GLUTEAL  NERVE. 

The  cutaneous  covering  of  the  gluteus  medius  and  mini- 
mus muscles  is  not  alone  supplied  by  the  gluteal  nerve,  as 
the  lumbar  nerves  may  be  seen  coursing  along  over  the  lower 
part  of  the  abdomen,  then  passing  over  the  crest  of  the  ilium, 
and  finally  reaching  this  part  of  the  thigh.  While  this  might 
seem,  at  a  first  glance,  to  be  a  peculiar  admixture  of  lumbar 
and  sacral  nerves,  yet,  on  returning  to  a  point  just  made,  we 
discover  that  the  superior  gluteal  nerve  is  of  lumbar  origin, 
although  apparently  a  branch  of  the  sacral  plexus;  hence, 
the  skin,  supplied  by  branches  of  lumbar  origin,  protects  all 
those  regions  to  which  muscular  branches  derived  from  the 
same  sources  can  be  traced.  We  see  the  region  of  the  gluteus 
maximus  muscle  apparently  avoided'  by  the  nerves  which 
descend  from  the  abdomen  to  supply  the  skin  of  the  adjoin- 
ing region,  and,  when  we  seek  for  an  explanation  of  the  fact, 
Ave  find  that  this  muscle  is  supplied  by  the  small  sciatic  nerve 
(derived  from  the  sacral  plexus,  and  having  no  connection 
with  the  lumbar  nerves) ;  hence,  the  integument  covering 
that  muscle  could  not  be  supplied  by  nerves  whose  source  of 
origin  would  prevent  a  perfect  sympathy  between  the  skin 
and  the  muscular  structures  which  it  covers. 

The  relation  of  this  nerve  to  the  gluteal  artery,  as  it  es- 
capes from  the  great  sacro-sciatic  foramen,  gives  it  a  surgical 

'  See  page  359  of  this  volume.  •  Hilton,  op  cii. 


DISTRIBUTION   OF  SUPERIOR   GLUTEAL  NERVE.       461 

importance,  as  that  vessel  is  sometimes  ligated  for  haemor- 
rhage from  some  of  its  branches. 

The  three  muscles  supplied  by  the  superior  gluteal  nerve, 
if  acting  in  connection  with  the  gluteus  maximus  muscle,  be- 
come the  abductors  of  the  hip  joint,  while  the  posterior 
half  of  the  gluteus  medius  and  the  posterior  fifth  of  the 
gluteus  minimus  assist  in  extension  of  the  thigh  upon  the 
trunk,  since  their  origin  lies  on  a  plane  posterior  to  their 
insertion  into  the  trochanter.  Thus  we  are  enabled  to  class 
the  superior  gluteal  nerve  as  a  factor  in  three  of  the  move- 
ments of  the  hip  joint,  viz.,  internal  rotation,  abduction,  and 
extension. 

When  the  superior  gluteal  nerve  is  subjected  to  irritation, 
a  spasmodic  condition  of  the  gluteal  muscles  may  be  pro- 
duced. It  is  extremely  rare  to  have  such  a  condition  devel- 
oped in  the  glutei  muscles  alone,  but  one  such  case  is  reported 
by  Remak.  In  this  case  the  spasms  of  the  legs  consisted  of  a 
series  of  gluteal  contractions  which,  when  the  patient  would 
attempt  to  walk,  would  draw  the  leg  backward  and  render  it 
fixed  in  that  position.  We  see,  however,  the  glutei  muscles 
frequently  affected  with  spasm  (in  connection  with  muscles  of 
the  lower  extremity  supplied  by  other  nerves)  in  tetanus, 
rheumatic  inflammation  of  the  hip  joint,  arthralgia,  neural- 
gia, and  lesions  within  the  pelvis  which  aifect  the  sacral 
plexus. 

The  gluteal  muscles  may  be  affected  with  paralysis,  but 
it  is  rare  that  the  paralysis  is  confined  exclusively  to  that 
region.  As  a  rule,  these  muscles  become  affected  as  the  result 
of  lesions  which  involve  the  sacral  plexus  to  a  greater  or  less 
extent,  such  as  spinal  diseases,  tumors  in  the  spinal  canal  or 
pelvis,  lesions  of  the  cauda  equina,  fractures  of  the  sacrum, 
fractures  of  the  pelvis,  etc.,  so  that  the  paralysis  of  the  glutei 
muscles  is  masked  by  a  similar  condition  of  muscles  supplied 
by  other  nerves.  When  the  glutei  muscles  are  paralyzed,  in 
connection  with  the  tensor  vaginae  femoris,  the  pyriformis, 
and  the  obturator  internus,  as  is  more  frequently  observed, 
the  rotation  of  the  thigh  inward  becomes  impossible,  and  out- 


462  THE  SPmAL  NERVES. 

ward  rotation  also  becomes  somewhat  impaired,  as  the  adduc- 
tor group  and  the  psoas  and  iliacus  have  chiefly  to  perform  it. 
Abduction  of  the  thigh  is  rendered  extremely  difficult,  and, 
if  the  paralysis  be  complete,  absolutely  impossible,  while  flex- 
ion of  the  thigh  is  impaired  and  limited  in  its  extent.  When 
such  patients  attempt  to  walk,  the  glutei  muscles  no  longer 
preserve  the  relations  of  the  trunk  to  the  thighs,  and  a  diffi- 
culty in  preserving  the  balance  is  therefore  present.  This  is 
especially  noticeable  when  an  attempt  to  ascend  a  flight  of 
steps  is  made,  as  the  trunk  has  then  to  be  inclined  forward. 
The  affected  muscles  usually  undergo  atrophy  when  thus  de- 
prived of  their  normal  power,  and  the  gluteal  region  loses  its 
natural  roundness  and  firmness. 

The  disturbances  of  sensibility  which  may  coexist  with 
this  type  of  paralysis  will  depend  somewhat  upon  the  seat  of 
the  exciting  cause,  as  well  as  upon  its  character.  Pain  may 
be  a  means  of  making  a  diagnosis  of  the  development  of  the  ex- 
citing lesion  before  the  paralysis  is  developed,  if  the  precepts 
given  you  in  the  earlier  lectures  of  this  course  be  applied, ' 
remembering  always  that  the  cause  of  the  pain  must  be  sought 
for  along  the  course  of  the  cutaneous  nerves  which  supply 
the  region  where  pain  is  felt,  and  that  the  omission  on  your 
part  of  one  of  the  nerves  whose  filaments  are  present  in  the 
region  of  pain  may  entail  a  complete  failure  in  discovering 
the  cause. 

THE   MUSCULAR  BRANCHES   OF  THE   SACRAL   PLEXUS. 

By  reference  to  the  table  of  the  distribution  of  the  vari- 
ous branches  of  the  sacral  plexus,'  you  will  perceive  that  five 
muscles  receive  a  direct  supply  from  it  through  branches  which 
are  not  specially  named,  being  included  in  the  muscular  set — 
these  five  muscles  being  the  pyriformis,  obturator  internus, 
gemellus  superior,  gemellus  inferior,  and  quadratus  femoris. 
If  we  consider  the  function  of  these  five  muscles,  it  will  be ; 
evident  that  they  should  receive  their  nerve  supply  from  the 
same  source,  provided  the  axiom  of  Hilton — that  the  nerve 

'  See  page  359  of  this  volume.  '  See  page  459  of  this  volume. 


MUSCULAR  BRANCHES  OF  THE  SACRAL  PLEXUS      463 

distribution  of  muscles '  is  a  guide  to  their  function — be  true, 
as  they  all  assist  in  the  external  rotation  of  the  thigh  by 
their  action  upon  the  great  trochanter  of  the  femur.  The 
situation  of  these  five  muscles  is  such  that  a  direct  supply 
from  the  sacral  plexus  might  almost  be  inferred.  The  pyri- 
formis  and  obturator  internus  muscles  arise  from  within  the 
pelvis  and  escape  from  its  cavity  by  means  of  the  greater 
and  lesser  sacro-sciatic  foramina,  while  the  two  gemelli 
muscles  and  the  quadratus  femoris  are  attached  to  the 
OS  innominatum  in  the  immediate  vicinity  of  these  two 
foramina.  Now,  the  sacral  plexus  lies  upon  the  pyriformis 
muscle,  and  would  naturally  supply  it,  while  the  other  four 
muscles  bear  such  an  intimate  relation  with  the  pyriformis, 
as  it  escapes  from  the  pelvis,  as  to  render  a  supply  from  the 
sacral  plexus  easy,  while  the  similarity  of  function  between 
the  ^NQ  muscles  would  presuppose  a  nerve  supply  from  the 
same  source. 

In  the  lectures  upon  the  obturator  and  anterior  crural 
nerves,  the  action  of  the  adductor  and  flexor  groups  of  mus- 
cles, in  assisting  the  external  rotation  of  the  thigh,  was  dis- 
cussed, and  we  here  come  upon  another  group  of  muscles 
which  also  tend  to  perform  the  same  movement  of  the  lower 
limb.  The  questions  may  arise  to  your  minds — how  are  we 
able  to  explain  a  dissimilarity  in  the  sources  of  motor  power 
in  groups  of  muscles  which  have  a  common  function  to  per- 
form %  How  are  we  able  to  reconcile  the  axioms  of  nerve 
supply,  so  often  quoted,  with  this  apparent  contradiction  ? 
The  answer  to  both  of  these  questions  is  settled  by  a  careful 
scrutiny  of  the  combined  actions  of  each  of  these  separate 
groups  of  muscles.  In  the  first  place,  the  five  muscles  of  the 
thigh,  supplied  by  the  sacral  plexus  of  nerves  through  its 
muscular  branches,  can  not  perform  the  movement  of  exter- 
nal rotation  of  the  thigh  when  the  subject  is  in  the  sitting 
posture.  It  is  in  this  relative  position  of  the  thigh  and  trunk 
that  the  adductor  group  of  muscles,  aided  by  the  psoas  and 
iliacus,  become  important  factors  in  the  movement  of  external 

J  Op.  cit. 


464  THE  SPINAL  NERVES, 

rotation ;  and  it  is  to  be  remembered  that  this  movement  is 
but  a  secondary  function  with  these  latter  muscles,  since  they 
are  designed  chiefly  to  insure  adduction  and  flexion  of  the 
thigh.  Each  muscle  of  a  group  is  usually  supplied  by  that 
nerve  whose  branches  are  also  distributed  to  others  of  that 
group  which  aid  in  its  primary  action,  rather  than  in  any 
secondary  movement  in  which  it  may  chance  to  participate  ; 
hence  the  psoas  and  iliacus  derive  their  power  from  the  ante- 
rior crural,  the  adductor  muscles  from  the  obturator,  and  the 
fiYQ  muscles  posterior  to  the  hip  joint  from  the  sacral  plexus, 
and  thus  the  primary  action  of  each  group  is  indicated  by  the 
nervous  supply,  as  well  as  by  the  points  of  origin  and  inser- 
tion of  each  muscle. 

THE  SMALL  SCIATIC   NERVE. 

This  branch  of  the  sacral  plexus  is  given  off  from  its  lower 
and  posterior  part,  and  escapes  from  the  pelvis  through  the 
sacro-sciatic  foramen,  below  the  pyriformis  muscle,  in  com- 
pany with  the  sciatic  vessels.  It  descends  beneath  the  gluteus 
maximus  muscle,  in  which  region  it  lies  to  the  inner  side  of 
the  great  sciatic  nerve,  and  continues  beneath  the  fascia  lata 
as  low  down  as  the  popliteal  space,  where  it  perforates  this 
fascia  and  joins  with  the  external  saphenous  nerve,  giving  off 
also  cutaneous  branches  of  its  own  to  the  popliteal  space  and 
the  back  of  the  calf. 

The  branches  of  this  nerve,  which  are  enumerated  in  the 
table,'  comprise  the  inferior  gluteal,  the  inferior  pudendal, 
and  the  cutaneous  filaments  distributed  over  the  gluteus  max- 
imus muscle,  and  the  regions  previously  mentioned.  The  fact 
that  this  nerve  supplies  the  gluteus  maximus  muscle  with 
motor  power  gives  it  an  importance  to  the  anatomist,  since 
this  muscle  is  one  of  the  most  important  factors  in  regulating 
the  position  of  the  trunk  and  the  lower  extremity  during  all 
the  various  attitudes  assumed  by  the  living  subject ;  but 
there  are  also  some  suggestions  of  value  which  have  been 
thrown  out  by  previous  authors  upon  anatomy  which  will 

^  Sec  page  459  of  this  volume. 


THE  SMALL  SCIATIC  NERVE. 


465 


merit  your  closest  attention,   especially  as  they  are  omitted 
ill  some  of  the  descriptive  text-books. 


Fig.  169. — The  small  sciatic  ncrvc^  loith  its  branches  of  distribution  and  termination. 

(Sappey.) 
1,  superior  gluteal  nerve;  2,  small  sciatic  nerve;  3,  3,  3,  branches  to  the  gluteus 
maximus ;  4,  branch  to  the  pyramidalis ;  5,  internal  pudendal  branch  of  the  small 
sciatic ;  6,  femoro-poplitcal  branch  of  the  same  nerve ;  Y,  7,  trunk  of  the  great  sci- 
atic ;  8,  branch  which  it  gives  to  the  long  head  of  the  biceps ;  9,  branch  to  the  short 
head  of  the  same  muscle ;  10,  10,  branch  to  the  semi-tendinosus  (the  latter  muscle 
has  been  divided  and  turned  back,  to  show  the  semi-membranosus) ;  11,  11,  branch 
to  the  semi-membranosus;  12,  12,  another  branch,  rising  from  the  common  trunk 
with  the  preceding  nerve,  and  passing  under  the  semi-membranosus  to  be  distributed 
to  the  adductor  magnus ;  13,  external  popliteal  nerve;  14,  internal  popliteal  nerve ; 
15,  filament  to  the  plantaris  ;  16,  16,  nerves  to  the  gastrocnemius;  IV,  origin  of  the 
external  saphenous  nerve. 

In  the  first  place,  this  nerve  sends  filaments  to  the  peri- 
nseum  and  genitals '  of  the  male  and  female,  after  supplying 

'  In  the  female,  the  filaments  probably  go  to  the  vulva  and  vagina  ;  but,  in  the  male, 
the  side  of  the  penis  is  thus  supplied. 


4:QG  THE  SPINAL  NERVES. 

the  gluteus  maximus  muscle  ;  and  the  suggestion  is  made  by 
Hilton,  in  reference  to  this  point,  that  the  action  of  this 
muscle  in  its  relation  to  coitus  may  tend  to  explain  the  neces- 
sity for  a  sympathy  between  these  two  parts  by  means  of  a 
common  nerve  supply. 

Again,  the  recognition  of  the  perineal  branch  of  the  small 
sciatic  nerve  is  sometimes  important  in  practice.  If  you  care 
to  trace  this  nerve  upon  the  dead  subject,  you  will  find  that 
it  escapes  from  beneath  the  perineal  border  of  the  gluteus 
maximus  muscle,  runs  along  the  outer  portion  of  the  peri- 
nseum,  and,  finally,  sends  cutaneous  filaments  to  the  sides  of 
the  penis.  The  perineal  region  is  also  sujiplied  by  the  peri- 
neal branches  of  the  pudic  nerve,  which  escape,  posteriorly 
to  those  of  the  sciatic,  from  beneath  the  same  muscle.  !N'ow, 
either  of  these  two  nerves  may  be  the  cause  of  a  pain  referred 
to  the  perinseum  and  the  penis,  and  their  points  of  escape 
from  beneath  the  gluteus  maximus  muscle  are  so  placed  as  to 
render  them  frequently  subjected  to  pressure  from  sitting 
upon  hard  or  uneven  seats.  It  is  thus  possible  for  pains, 
referred  to  the  penis,  to  be  wrongly  attributed  to  diseases  of 
the  bladder,  calculus  in  the  bladder,  urethral  troubles,  and 
all  other  types  of  disease  which  are  commonly  indicated  by 
more  or  less  pain  in  that  locality,  when  the  cause  may  be 
found  and  correctly  diagnosed  by  following  up  the  course  of 
the  perineal  branch  of  the  small  sciatic.  Such  a  case  is 
reported  by  Hilton,  where  prominent  surgeons  of  Europe, 
among  them  Mr.  Key,  had  diligently  and  unsuccessfully 
searched  for  the  cause  of  a  pain,  referred  to  the  penis,  along 
the  course  of  the  pudic  nerve,  and  where  the  patient  had 
been  treated  for  disease  of  the  bladder,  a  careful  examination 
subsequently  revealing  the  true  cause  to  be  a  spot  of  hardened 
tissue  pressing  upon  the  peiineal  branch  of  the  small  sciatic 
nerve,  which  was  cured  (as  well  as  the  pain  which  it  created) 
by  the  application  of  nitric  acid  over  the  seat  of  thickening. 
It  is,  therefore,  well  to  remember  the  course  of  this  branch, 
as  well  as  those  of  the  pudic  nerve,  when  investigating  for  the 
cause  of  pain  in  the  penis  or  perinjeum. 


THE  PUDIG  NERVE.  467 

THE   PUDIC   KERVE. 

This  brancli  of  the  sacral  plexus  arises  from  its  lower  part, 
and  immediately  escapes  from  the  pelvis  by  means  of  the 
great  sacro-sciatic  foramen  in  company  with  the  pudic  artery, 
the  sciatic  vessels  and  nerves,  and  the  gluteal  vessels  and 
nerves.  The  situation  of  the  nerve  in  this  foramen  is  on  the 
inner  side  of  the  great  sciatic  nerve,  both  of  which  escape 
through  the  lower  part  of  the  foramen,  beneath  the  pyri- 
formis  muscle.  The  pudic  nerve  then  reenters  the  pelvis 
through  the  lesser  sacro-sciatic  foramen,  in  company  with  its 
artery,  and  immediately  gives  off  its  inferior  hemorrhoidal 
branch.  From  this  point  the  nerve  passes  along  the  outer 
wall  of  the  ischio-rectal  fossa,  lying  above  the  pudic  artery 
(both  artery  and  nerve  being  covered  by  the  obturator  fas- 
cia), and  divides  into  the  perineal  branch  and  the  dorsal  nerve 
of  the  penis. 

Of  these  three  branches  of  the  pudic  nerve,  the  distribu- 
tion has  been  given  in  a  previous  table,  but  with  less  detail 
than  the  subject,  perhaps,  demands. 

The  inferior  hemorrhoidal  nerve  occasionally  arises  di- 
rectly from  the  sacral  plexus  rather  than  as  a  branch  of  the 
pudic ;  its  course  runs  along  the  ischio-rectal  fossa,  and  it  is 
distributed  to  the  sphincter  muscles  of  the  rectum  and  the 
skin  around  the  region  of  the  anus.  It  communicates  freely 
in  this  region  with  the  superficial  perineal  and  inferior  pu- 
dendal nerves. 

The  perineal  nerve  is  the  largest  branch  of  the  pudic,  and 
accompanies  the  superficial  perineal  artery.  It  divides  into 
two  sets  of  terminal  filaments — the  cutaneous  or  superficial 
perineal  nerves  and  muscular  branches.  The  former  of  these 
give  a  few  twigs  to  the  sphincter  ani  and  levator  ani  muscles, 
but  are  chiefly  distributed  to  the  integument  of  the  perinseum, 
scrotum,  labium,  and  the  penis,  communicating  freely,  in  the 
region  of  the  anus,  with  the  inferior  hemorrhoidal  nerve. 
The  muscular  branches  usually  arise  from  the  pudic  nerve 
by  a  common  trunk,  which  passes  forward  and  inward  un- 


468  THE  SPINAL  NERVES. 

derneath  the  transverse  perinei  muscle ;  its  terminal  fila- 
ments are  given  off  to  the  transverse  perinei,  erector  penis, 
accelerator  urinse,  and  compressor  urethrse  muscles,  and  a 
twig  is  often  sent  to  the  bulb  of  the  urethra. 

The  dorsal  nerve  of  the  penis  is  the  smaller  terminal  fila- 
ment of  the  pudic  nerve,  which  accompanies  the  pudic  artery 
along  the  rami  of  the  pubes  and  ischium,  between  the  layers 
of  the  deep  perineal  fascia ;  it  then  pierces  the  suspensory  lig- 
ament of  the  penis  and  continues  its  way  along  the  dorsum  of 
that  organ  as  far  as  the  glans  penis.  It  gives  a  branch  to  the 
corpus  cavernosum,  and  supplies  the  integument  of  the  dor- 
sum ^  of  the  penis ;  in  the  female  the  course  of  the  nerve  is 
about  the  same,  although  the  size  of  the  nerve  is  smaller, 
since  the  clitoris  is  minute  in  its  size  as  comj)ared  with  the 
organ  of  the  male. 

CLINICAL   POINTS   PERTAINING  TO  THE   PUDIC   NERVE. 

A  careful  study  of  the  distribution  of  the  various  branches 
of  this  nerve  will  show  that  it  is  the  source  of  motion  to  the 
muscles  of  the  perinseum  and  urethra,  and  of  sensation  to  the 
integuinent  of  the  perinseum,  scrotum,  labium,  penis,  and  the 
mucous  covering  of  the  clitoris,  as  well  as  that  lining  the 
urethral  canal.  The  friction  made  upon  the  cutaneous  nerves 
of  the  external  genital  organs  in  the  acts  of  sexual  intercourse 
and  masturbation  creates  a  reflex  act  within  the  spinal  cord, 
which  creates  the  turgidity  of  the  penis  and  clitoris  during  the 
first  portion  of  those  acts  ;  and,  later  on,  a  series  of  muscular 
contractions  in  the  perineal  muscles  and  the  involuntary  mus- 
cular fiber  of  the  urethral  canal  are  produced,  which  assist  in 
the  expulsion  of  semen,  in  the  male,  and  the  secretion  of  the 
glands  of  Bartholine  in  the  female.  That  this  is  the  true 
explanation  of  emission  is  evidenced  by  the  fact  that  onan- 

'  Hilton  Btatcs  that  tlic  integument  of  the  sides  of  the  penis  is  supplied  by  the  perineal 
bmnch  oi  the  iji/cvior  ffhtieed  nerve,  and  from  no  other  source.  This  statement  differs 
from  most  of  the  standard  authors,  but  it  seems  to  be  supported  by  clinical  demonstra- 
tion. The  reader  is  referred  to  page  466  of  this  volume,  where  the  subject  is  discussed 
from  its  physiological  and  clinical  point  of  view.' 


THE  GREAT  SCIATIC  NERVE.  469 

ism  is  most  effectually  prevented  by  blistering  the  cutaneous 
covering  of  the  penis  and  the  mucous  covering  of  the  clitoris. 

In  some  cases  of  fracture  of  the  spine,  in  the  dorsal  region, 
where  a  part  of  the  spinal  marrow  is  left  intact  below  the  seat 
of  fracture,  you  may  be  able,  by  repeatedly  pinching  the  skin 
of  the  scrotum  and  penis,  to  produce  spasmodic  contractions 
of  the  muscles  of  the  perinseum  and  urethra,  and  often  to 
ect  a  turgidity  of  the  genital  organ  to  such  a  degree  as  to 
make  it  resemble  an  imperfect  erection  or  priapism. 

The  ejaculation  of  the  last  few  drops  of  urine  from  the 
urethra  is  unquestionably  effected  by  a  reflex  act  through  the 
sensory  and  motor  fibers  of  the  pudic  nerve,  in  consequence 
of  the  irritation  produced  in  the  sensory  fibers  of  the  urethral 
mucous  membrane  from  pressure  of  the  urine  or  the  contact 
of  its  saline  ingredients. 

It  is  not  uncommon  for  rectal  disease  to  produce  sympa- 
thetic manifestations  in  the  genito-urinary  organs,  in  the  form 
of  neuralgic  pains,  involuntary  emissions,  incontinence  of 
urine,  etc.;  such  effects  can  only  be  explained  by  the  dis- 
tribution of  the  pudic  nerve  to  the  integument  about  the  anus 
(and,  I  believe,  to  the  walls  of  the  rectum  also),  which  allows 
reflex  motor  impulses  to  be  sent  from  the  spinal  cord,  in 
response  to  rectal  irritation,  to  the  genito-urinary  organs  and 
perineal  muscles. 

THE   SCIATIC  NERVE. 

This  nerve  arises  from  the  lumbo-sacral  cord  and  the  four 
upper  sacral  nerves,  and  is  a  direct  continuation  of  the  sacral 
plexus.  It  escapes  from  the  pelvis  through  the  great  sacro- 
sciatic  foramen  below  the  pyriformis  muscle,  lying  on  the 
outer  side  of  the  pudic  vessels  and  nerve.  It  then  passes 
downward  between  the  trochanter  major  of  the  femur  and  the 
tuberosity  of  the  ischium,  lying  behind  the  external  rotator 
muscles  of  the  hip  joint  and  the  adductor  magnus,  to  the 
lower  third  of  the  back  of  the  thigh,  where  it  divides  into  its 
two  terminal  branches,  the  external  and  internal  popliteal 
nerves. 

32 


I 


470 


THE  SPINAL  NERVES. 


In  the  lower  two  thirds  of  its  course,  it  is  covered  by  the    ' 
lower  fibers  of  the  gluteus  maxim  us  and  biceps  muscles.     It    - 


Fig.  170. — The  great  sciatic  nerve,  with  its  branches  of  distribution  and  termination. 

(Sappey.) 
1,  superior  gluteal  nerve;  2,  small  sciatic  nerve;  8,  3,  3,  branches  to  the  gluteus 
niaximus ;  4,  branch  to  the  pyramidalis ;  5,  internal  pudendal  branch  of  the  small 
sciatic ;  6,  femoro-popliteal  branch  of  the  same  nerve ;  1,  7,  trunk  of  the  great  sci- 
atic ;  8,  branch  which  it  gives  to  the  long  head  of  the  biceps ;  9,  branch  to  the  short 
head  of  the  same  muscle ;  10,  10,  branch  to  the  semi-tcndinosus  (the  latter  muscle 
has  been  divided  and  turned  back,  to  show  the  semi-membranosus) ;  11,  11,  branch 
to  the  semi-membranosus;  12,  12,  another  branch,  rising  from  the  common  trunk 
with  the  preceding  nerve,  and  passing  under  the  semi-membranosus  to  be  distributed 
to  the  adductor  magnus ;  13,  external  popliteal  nerve;  14,  internal  popliteal  nerve; 
15,  filament  to  the  plantaris  ;  16,  16,  nerves  to  the  gastrocnemius;  17,  origin  of  the 
external  saphenous  nerve. 

gives  off  branches  to  the  hamstring  muscles  and  the  adductor 
magnus,  and  some  articular  branches  to  the  back  of  the  hip 
joint.     The  two  tables  which  I  now  show  you  are  designed  to 


DISTRIBUTION  OF  THE  SCIATIC  NERVE. 


471 


illustrate  the  branches  given  off  by  the  external  and  internal 
popliteal  nerves.  The  former  of  these  is  the  smaller  of  the  two, 
and  passes  along  the  outer  side  of  the  popliteal  space  close  to 
the  biceps  muscle,  while  the  other  traverses  the  middle  of 
the  popliteal  space  as  far  as  the  lower  border  of  the  popliteus 
Lscle,  where  it  becomes  the  posterior  tibial  nerve. 


Fig.  171. —  TJie  external  popliteal  nerve.  (Sappey.) 
I,  external  popliteal  nerve  ;  2,  peroneal  or  cutaneous  branch  ;  3,  communicaus  peronei ; 
4,  external  saphenous  nerve  ;  5,  trunk  formed  by  the  junction  of  the  external  saphe- 
nous with  the  commuuicans  peronei ;  6,  calcanean  branch  rising  from  the  trunk  ; 
7,  external  terminal  branch  of  the  trunk  on  its  way  to  form  the  external  doisil 
branch  of  distribution  to  the  fifth  toe ;  8,  its  internal  terminal  branch  which  forms 
the  internal  dorsal  branch  for  the  fifth  toe  and  the  external  dorsal  branch  for  the 
fourth  toe;  9,  9,  musculo-cutaneous  nerve;  10,  10,  its  terminal  branches;  11,  anas- 
tomosis of  its  external  terminal  branch  with  the  external  saphenous  ;  12,  anastomosis 
of  its  internal  and  external  terminal  branches  with  each  other;  13,  anterior  tibial 
nerve;  14,  terminal  portion  of  this  nerve,  anastomosing  with  the  musculo-cutaneous, 
and  dividing  to  form  the  deep  branches  of  distribution  on  the  dorsum  of  the  foot  to 
the  internal  side  of  the  great  toe  and  the  external  side  of  the  second  toe. 


472 


TEE  SPINAL  NERVES. 


KERVES   OF  THE   LEG   AND   FOOT. 


EXTERXAL 

POPLITEAL 

NERVE. 

(Peroneal 

NERVE.) 


Articular  branches. 
Cutaneous  branches. 


Anterior    Tibial 
Nerve. 


(4) 


MUSCULO-CUTANEOUS 

Neuve. 


INTERNAL 

POPLITEAL 

NERVE. 


Articular  . 
Muscular   . 


External   Saphe- 
nous Nerve. 


Three  in  number, 
Distributed  to  knee  joint. 
j;  Two  or  three  in  number, 
•]  Supply  integument  of  outer  and  back  part  of 
(       the  leg. 

r  Muscular  (to  muscles  in  front  part  of  Ice; 
1       and  to  the  peroneus  tertius). 

External  j  Extensor  brevis  digitorum, 
branch.   \  Articulations  of  the  tarsus. 
Internal  j  /^i^f^fwwm/ of  the  adjoining  side- 
^     branch.    (      of  the  great  and  2d  toes. 
(  T,r       1       \  Peroneus  loncus, 
Muscular,  -j  ^^^.^^^^^  brevis. 

( Intec/ument  of  outer  side  of  foot 
Extei-nal]      and  ankle, 
branch.  ]  Integument  of  the  adjoining  sidc- 
(^      of  od,  4th,  and  5th  toes, 
r  Integument  of  the  inner  side  of 
J.  ,     I       the  foot  and  ankle, 

InternaC    ^  jntcgument  oi  the  Sidiommu  sidv 
branch.  .      ^j.  ^^  ^^^^  gj  ^^^g  ^^^^  j,^j^^.^. 


(4)  Posterior  Tihial 
Nerve. 


side  of  great  toe. 

Three  in  number. 

Distributed  to  knee  joint. 

Gastrocnemius, 

Plantaris, 

Soleus, 

Popliteus. 

Formed  by  two  filaments,  one  from  each  of 

the  popliteal  nerves. 
Integument  of  the  outer  side  of  foot  and  the 

little  tee. 

!  Flexor  longus  pollicis. 
Flexor  longus  digitorum, 
Tibialis  posticus. 
Plantar       \  Integummt  of  heel  and  inner  pan 
cutaneous.  |      of  sole  of  foot. 

fxx.  ..  1  (  Intequmeni  of  the 

^'f  *^^  u        \      4  toes  on  inner 
branches. .  ]      ^.^^  ^^  ^^^^^ 

Flexor  brevis  digi- 
torum, 
Abductor  pollicis, 
-{  Flexor  brevis  pol- 
licis. 
Two  inner  lumbri- 
calcs  muscles. 
Articular  (to  tarsus), 
Cutaneous  (to  sole  of  foot). 

'  Flexor  accessor! r 
,  Abductor     minii 
I       digiti. 
U  outer  toes, 
Flexor  brevis  mini- 
mi digiti. 
4th      interosscd 

muscle. 

'yd   and   4th    h,: 

bricalos. 

Deep  J  Rest  of  interos? 

branch.  I  Adductor  poUiti 

1^  [Transversus  pcil 


Internal 

PLANTAR. 


External 

PLANTAR. 


Muscular 


Muscular 


Supei'fcial 
branch. 


TEE  NERVES   OF  THE  LEG. 


473 


If  yon  will  study  these  tables,  you  will  perceive  that  the 
external  popliteal  nerve  distributes  articular  branches  to  the 


Fig.  172. —  T7ie  internal  popliteal  nerve.     (Sappey.) 

1,  trunk  of  the  great  sciatic  ;  2,  external  popliteal ;  3,  internal  popliteal ;  4,  4,  branches 
to  the  gastrocnemius^ — both  nerves  and  muscle  have  been  divided  ;  5,  origin  of  the 
external  saphenous ;  6,  branch  to  the  solcus,  divided  together  with  the  muscle ;  7, 
internal  popliteal  nerve  passing  through  a  fibrous  ring  in  the  soleus ;  8,  8,  branch 
springing  from  the  lower  portion  of  this  nerve,  and  likewise  passing  through  the 
fibrous  ring  of  the  soleus.  At  this  level  it  gives  off  a  reflected  or  ascending  division, 
which  penetrates  the  popliteus  at  its  deep  surface,  but  is  not  seen  in  the  cut,  and  a 
more  slender  descending  division  which  makes  its  way  through  the  interosseus  mem- 
brane and  supplies  the  tibialis  auticus  muscle  ;  9,  9,  posterior  tibial  nerve  ;  10,  10, 
branches  which  it  furnishes  to  the  flexor  longus  digitorum ;  11,  11,  branches  which 
it  gives  off  to  the  tibialis  posticus  muscle  ;  12,  12,  branches  to  the  flexor  longus  pol- 
licis ;  13,  calcanean  branches ;  14,  terminal  extremity  of  the  external  saphenous 
nerve. 

knee  joint,  and  cutaneous  filaments  to  the  outer  and  back 
part  of  the  leg.     The  two  main  nerve  trunks  which  arise  from 


4Y4  THE  SPINAL  NERVES. 

it  are  called  the  anterior  tibial  and  the  musculo-cutaneons, 
both  of  which  are  given  off  from  the  main  trunk  after  it 
pierces  the  peroneus  longus  muscle  about  one  inch  below  the 
head  of  the  fibula,  although  three  articular  and  several  cuta- 
neous filaments  also  arise  from  it.  You  will  also  perceive 
that  four  main  branches  are  given  off  from  the  internal  pop- 
liteal nerve,  viz.,  articular  and  muscular  branches,  and  the  ex- 
ternal saphenous  and  posterior  tibial  nerves.  The  muscular 
filaments  supply  four  muscles  in  the  immediate  vicinity  of 
the  knee,  while  the  articular  filaments,  as  in  the  preceding 
nerve,  are  distributed  to  the  knee  joint.  Other  points  of 
interest  might  be  specially  designated  as  comprised  in  these 
pages,  but  they  will  be  considered  in  their  practical  relations 
when  the  clinical  points  which  are  presented  by  the  nerves  of 
the  lower  extremity  are  considered. 

I  desire  to  call  your  attention,  first,  to  the  fascia  of  the 
leg,  into  which  three  muscles  of  the  thigh  are  inserted, 
viz.,  the  sartorius,  the  gracilis,  and  the  semi-tendinosus.  I 
have  already  called  your  attention  to  the  fact  that  the  fas- 
ciae of  the  body  are  always  to  be  regarded  as  one  of  the 
points  of  insertion  of  the  muscles  which  are  attached  to 
them ;  now,  if  this  be  true,  and  it  undoubtedly  is  so,  we 
ought  to  discover  a  particular  distribution  of  the  cutaneous 
nerves  at  this  point,  since  the  nerves  which  supply  the  mus- 
cles supply  also  the  skin  over  the  insertion  of  the  same  mus- 
cles. We  shall  find,  on  dissection  of  this  region,  that  the 
long  saphenous,  the  obturator,  and  a  branch  of  the  sciatic 
nerves  are  distributed  in  the  skin  of  the  calf ;  the  one  de- 
rived from  the  anterior  crural  (which  supplies  the  sartorius), 
another  a  filament  of  the  obturator  (which  supplies  the  gra- 
cilis), and  the  third  derived  from  the  sciatic  (since  it  supplies 
the  semi-tendinosus  muscle).  These  three  nerves,  therefore, 
supply  both  the  fascia  of  the  leg  and  the  skin  on  the  inner 
side  of  the  leg  below  the  knee  joint ;  hence,  pain  in  this  re- 
gion must  be  sought  for  along  the  course  of  one  of  these  three 
nerves.  It  is  too  common  among  physicians  to  regard  a  pain 
which  is  localized  at  the  inner  side  of  the  knee  as  dependent 


THE  NERVES  OF  THE  LEG. 


475 


upon  the  obturator  nerve,  to  the  exclusion  of  the  sciatic  or 
the  anterior  crural ;   but   anatomy  clearly  teaches  us  that 


Fig.  1Y3. — The  external  saphenous  nerve  audits  accessory^  the  communicans  peronei. 

(Sappey.) 

1,  internal  popliteal  nerve  ;  2,  nerve  to  the  external  head  of  the  gastrocnemius  ;  3,  nerve  to 
the  internal  head  ;  4,  external  saphenous  nerve ;  5,  external  popliteal  nerve ;  6, 
communicans  peronei ;  7,  peroneal  or  cutaneous  branch  ;  8,  branch  sometimes  given 
off  by  the  external  saphenous  to  the  fourth  and  fifth  toe ;  9,  trunk  formed  by  the 
junction  of  the  communicans  peronei  with  the  external  saphenous ;  10,  calcanean 
branch  given  off  by  this  trunk  ;  11,  plantar  cutaneous  branch  of  the  posterior  tibial; 
12,  internal  saphenous  nerve  ;   13,  13,  13,  posterior  branches  of  this  nerve. 

there  are  three  possible  lines  of  direction,  which  we  are 
bound  to  explore  in  searching  for  the  situation  of  the  real 
cause  which  is  producing  it.  We  should  always  carefully 
examine  all  the  anatomical  relations  of  the  obturator,  the 
sciatic,  and  the  anterior  crural  nerves,  in  order  to  ascertain,  if 
possible,  the  real  cause  of  pain  which  is  expressed  on  the  in- 


476 


THE  SPINAL  NERVES. 


ner  side  of  the  knee  joint,  and  the  axiom  of  nerve  distribu- 
tion, which  was  first  pointed  out  by  Hilton,  and  to  which  I 
have  frequently  directed  your  attention,  offers  us,  in  this 
instance,  as  in  many  others,  a  simple  rule  which  should 
guide  us  in  searching  for  the  cause  of  pain  before  we  attempt 
measures  for  its  relief. 


Fig.  1*74. —  The  plantar  nerves,  their  course,  anastomoses,  and  distribution.     (Sappcj.) 

1,  internal  plantai'  nerve  ;  2,  2,  branches  which  it  gives  to  the  abductor  pollieis  ;  3,  branch 
which  it  gives  to  the  accessorius ;  4,  branch  to  the  flexor  brevis  digitoruni ;  5,  branch 
of  distribution  to  the  internal  plantar  surface  of  the  great  toe  ;  6,  another  branch  of 
the  internal  plantar  dividing  into  three  secondary  portions,  which  subdivide,  in  their 
turn,  to  form  the  branches  of  distiibution  on  the  plantar  surface  to  the  outer  side  of 
the  groat  toe,  both  sides  of  the  second  and  third  toes,  and  the  inner  side  of  the 
fourth  toe  ;  7,  external  plantar  nerve ;  8,  8,  branches  which  it  sends  off  to  the 
abductor  minimi  digiti ;  9,  branch  to  the  accessorius;  10,  branch  of  distribution  on 
the  plantar  surface  to  the  outer  side  of  the  little  toe;  11,  another  branch  of  the  same 
nerve  dividing  to  supply  the  inner  side  of  the  little  toe  and  the  outer  side  of  the  fourth 
toe ;  12,  anastomosis  of  the  internal  with  the  external  plantar  ;  13,  origin  cf  the  deep 
branch  of  the  external  plantar. 

I  have  found,  in  several  instances,  that  local  ansesthetics, 
when  applied  to  the  skin  over  the  seat  of  pain,  frequently 
have  the  power  of  relieving  a  sense  of  distress  in  other  re- 
gions apparently  far  removed  from  it,  but  still  connected 
with  the  seat  of  pain  by  means  of  a  nervous  communication. 
Thus,  in  disease  of  the  hip  joint,  an  anodyne  applied  in  the 


CLINICAL   POLNTS  AFFOBDED  BY  NERVES  OF  LEG.    477 

region  of  the  knee  joint  will  often  relieve  symptoms  whicli 
are  referable  to  the  hip,  and  we  can  only  attribute  this  effect 
to  a  benumbing  influence  exerted  by  means  of  the  sciatic  and 
obturator  nerves  upon  that  joint,  since  both  of  these  nerves 
send  articular  filaments  to  it,  as  well  as  cutaneous  filaments 
to  the  region  of  the  knee. 

In  some  instances,  where  abnormalities  of  origin  of  nerve 
filaments  can  be  detected,  I  believe  that,  if  you  will  trace  the 
nerve  upward  for  some  distance  toward  the  spinal  marrow, 
you  will  find  that  the  cutaneous  filaments  of  the  nerve,  which 
apparently  has  an  abnormal  origin,  are  in  intimate  communi 


Fig.  iTo, — T.'ie  deep  branch  of  the  external  plantar 


(Sappcy.) 


1,  internal  plantar  nerve  ;  2,  its  internal  branch  ;  3,  its  external  branch,  whose  two  divis- 
ions have  been  cut,  together  with  the  adductor  pollicis,  to  show  the  deep  branch  of 
the  external  plantar;  4,  trunk  of  the  external  plantar;  5,  its  superficial  branch, 
which  divides  almost  immediately  into  two  secondary  branches,  distributed  to  the 
fourth  and  fifth  toes  ;  6,  its  deep  "branch,  distributed  to  the  adductor  poUicis,  trans- 
vcrsus  pedis,  and  the  intcrossei ;  7,  branches  to  the  adductor  pollicis ;  8,  8,  branches 
to  the  interossei ;  9,  branches  to  the  transvcrsus  pedis, 

cation  with  the  nerve  trunk  whose  functions  are  assisted  by 

them,  and  from  which  its  most  frequent  origin  can  be  verified. 

If  we  examine  the  anatomy  of  the  hip  joint,  we  shall  find 


478  THE  SPINAL  NERVES. 

that  a  branch  of  the  anterior  crural  nerve  passes  in  close  rela- 
tion with  its  capsule,  if  it  is  not  intimately  associated  with 
it ;  that  a  branch  of  the  obturator  nerve  supplies  its  capsular 
ligament,  and  is  ultimately  distributed  to  the  ligamentum 
teres ;  and,  finally,  that  a  branch  from  the  sacral  plexus  sup- 
plies the  hip  joint  at  its  posterior  aspect,  after  sending  fila- 
ments to  the  gemelli,  the  quadratus  f  em  oris,  and  the  obtu- 
rator internus  muscles.  The  study  of  the  anatomy  of  Joints 
is  of  particular  importance  to  the  diagnostician,  since  it  fre- 
quently explains  how  remote  sympathetic  pains  may  be 
dependent  upon  irritation  of  articular  branches  of  a  nerve, 
whose  terminal  cutaneous  filaments  are  distributed  to  other 
regions,  often  far  removed  from  the  joint  which  it  supplies. 
We  know  that  disease  of  the  hip  joint,  which  is,  perhaps, 
one  of  the  most  frequent  which  we  meet  with  in  practice,  is 
often  manifested,  in  its  early  stages,  by  a  pain  which  is  re- 
ferred to  the  knee ;  and  we  can  understand,  from  what  has 
previously  been  said,  that  this  sensation  of  pain  must  be 
transmitted  through  one  of  three  sources,  viz.,  the  obturator, 
anterior  crural,  or  the  sciatic  nerves. 

CLINICAL   POINTS    PERTAINING   TO   THE   NERVES    DERIVED    FROM   THE 
SCIATIC,    OR  TO   THE   SCIATIC   NERVE   ITSELF. 

The  morbid  conditions  of  the  sciatic  nerve  or  its  branches 
which  are  most  frequently  met  with  comprise  :  1,  neuralgia^ 
which  may  be  articular  or  confined  to  the  direct  course  of  the 
sciatic  nerve  ;  2,  spasmodic  affections  of  the  muscles  supplied 
by  the  sciatic  nerve  or  its  branches  ;  and  3,  paralysis  of  the 
different  muscles  supplied  by  the  various  nerve  trunks. 


SCIATICA. 

This  type  of  neuralgia — to  which  the  name  "malum  Co- 
tunnii "  is  sometimes  applied — may  affect  the  greater  portion 
of  the  back  part  of  the  thigh,  a  part  of  the  gluteal  region,  the 
knee  joint  and  patella,  the  anterior,  lateral,  and  posterior 
surfaces  of  the  leg,  and  the  whole  of  the  foot,  with  the  excep- 


SCIATIC  NEURALGIA.  479 

tion  of  its  internal  border,  which  derives  its  nerve  supply 
from  the  saphenous  branch  of  the  anterior  crural  nerve.  It 
is  seldom  that  all  of  these  regions  are  affected  at  the  same 
time,  since  the  nerve  may  be  subjected  to  a  source  of  irrita- 
tion which  affects  only  individual  branches.  The  most  fre- 
quent seat  of  pain  is  confined,  as  a  rule,  to  the  posterior  sur- 
face of  the  thigh  and  the  upper  half  of  the  calf  of  the  leg ; 
but  the  external  surface  of  the  lower  half  of  the  leg  and  the 
corresponding  part  of  the  foot,  as  well  as  the  sole,  are  often 
the  seat  of  a  neuralgic  pain  which  is  of  a  severe  type.  The 
disease  is  usually  unilateral  in  character,  and,  if  bilateral,  a 
central  cause  may  be  suspected. 

Among  the  causes  of  this  type  of  neuralgia  may  be  men- 
tioned exposure  to  cold  and  dampness,  malarial  affections, 
inflammations  of  the  nerve,  injuries,  pressure  of  tumors  or 
inflammatory  exudations,  violent  exertion,  disturbances  of 
the  venous  circulation  of  the  pelvis,  and  mechanical  pressure 
from  sitting  upon  hard  or  uncomfortable  seats,  uterine  dis- 
placement, pelvic  tumors,  aneurism,  and  hernia. 

The  beginning  of  this  disease  is  usually  associated  with 
premonitory  symptoms,  among  which  may  be  mentioned  a 
sensation  of  stiffness,  cold,  or  heat  in  the  affected  regions, 
with  occasional  feelings  of  formication,  or  a  fluid  trickling 
over  the  skin.  Soon  painful  electric  pains  are  experienced, 
which  show  a  marked  paroxysmal  character.  These  attacks 
occasionally  occur  without  warning  or  premonitory  symp- 
toms. The  pain  is  remarkably  violent,  and  of  a  tearing  and 
lancinating  character,  and  usually  follows  the  direction  of 
the  nerve  trunk  which  is  affected.  It  often  changes  its  seat 
of  greatest  intensity,  and  the  lines  which  connect  the  spots  of 
greatest  x)ain  will  generally  conform  to  the  anatomical  course 
of  the  affected  nerve.  The  pain  is  usually  markedly  increased 
by  motion  of  the  muscles,  and  the  paroxysms  seem  to  be  ex- 
cited by  the  most  trivial  causes,  such  as  a  draft  of  cold  air, 
coughing,  sneezing,  sudden  bending  of  the  body,  the  contact 
of  the  clothes  with  the  skin,  or  straining  during  the  acts  of 
defecation  or  micturition.     If  the  whole  area  of  the  distribu- 


480 


THE  SPINAL  NERVES. 


tion  of  the  sciatic  nerve  be  involved,  the  pain  occurs  with 
special  violence  first  in  one  and  then  in  another  branch,  while 
the  posterior  branches  of  the  sacral  nerves  may  be  also  impli- 
cated, and  the  patient  complain  of  violent  pain  in  the  sacrum 
and  the  loins. 


8... ..J. 


-  jl^ 


12 


Fig.  176. —  TJie  motor  points  on  tlic  posterior  aspect  of  the  thigh. 
1,  branch  of  the  inferior  gluteal  nerve  to  the  gluteus  maximus  muscle;  2,  sciatic  nerve; 
3,  long  head  of  biceps  muscle ;  4,  short  head  of  biceps  muscle ;  5,  adductor  magnus 
muscle  ;  6,  scmi-tendinosus  muscle ;  7,  serai-membranous  muscle ;  8,  tibial  nerve ; 
9,  peroneal  nerve;  10,  external  head  of  gastrocnemius  muscle;  11,  soleus  muscle; 
1 2,  internal  head  of  gastrocnemius  muscle. 


As  has  been  mentioned  in  other  forms  of  neuralgia,  certain 
painful  points  may  usually  be  detected,  which  are  diagnostic 
of  neuralgia  from  those  severe  pains  which  accomi)any  the 
early  stages  of  locomotor  ataxia.  The  most  constant  point  of 
sensitiveness  to  pressure  is  stated  by  Valleix  to  correspond  to 
the  posterior  superior  spine  of  the  ilium  ;  another  usually  ex- 


SPASM  OF  THE  LOWER  LIMB.  481 

ists  where  the  nerve  escapes  from  the  cavity  of  the  pelvis  ;  a 
third  is  often  found  at  the  lower  border  of  the  gluteus  maxi- 
mus  muscle,  where  the  posterior  cutaneous  branch  emerges ; 
the  fourth  corresponds  to  the  head  of  the  fibula,  where  the 
tibial  nerve  is  given  off  ;  a  fifth  point  is  often  discovered  be- 
hind the  internal  malleolus ;  and,  finally,  there  are  frequent 
inconstant  points  in  the  thigh,  on  the  calf  of  the  leg,  and  on 
the  dorsum  of  the  foot,  all  of  wMch  correspond  to  localities 
where  cutaneous  branches  either  divide  or  perforate  some 
fascia. 

In  connection  with  this  neuralgic  pain,  certain  motor 
symptoms  are  frequently  developed.  These  comprise  a  pe- 
culiar limping  gait,  a  mode  of  carrying  the  leg  which  is  quite 
diagnostic,  cramp  of  various  degrees,  and  possibly  convul- 
sions, which  are  sometimes  very  violent.  These  symptoms 
are  the  result  of  direct  and  reflex  irritation,  and  may  be  the 
forerunners  of  a  condition  of  paresis  or  of  actual  paralysis. 

Among  the  vaso-motor  disturbances  which  accompany  this 
disease  may  be  mentioned  paleness  and  coldness  of  the  skin, 
in  some  instances  accompanied  by  numbness  and  chilly  sen- 
sations, and  in  other  cases  redness  and  heat  of  the  skin,  with 
increased  perspiration,  increased  growth  of  the  hair,  herpes 
zoster  along  the  course  of  the  affected  nerve,  a  saccharine  con- 
dition of  the  urine,  and  hypertrophy  and  atrophy  of  the 
muscles. 

Sciatica  is  to  be  diagnosed  from  disease  of  the  hip  Joint ; 
from  locomotor  ataxia  in  its  early  stages ;  from  muscular 
rheumatism ;  and  the  pains  of  spinal  disease,  affecting  the 
lateral  columns,  when  the  patient  is  subjected  to  extreme  ex- 
ertion. 

SPASM   OF  THE   LOWER   LIMBS. 

The  muscles  of  the  hip — especially  the  psoas,  iliacus, 
quadratus  lumborum,  and  adjacent  muscles  of  the  anterior 
surface  of  the  thigh — may  be  the  seat  of  tonic  spasm,  which 
has  been  named  by  Stromeyer  "spasmodic  contracture  of  the 
hip."  It  may  follow  an  inflammation  or  neuralgia  of  the  hip 
joint,  psoas  abscess,  or  diseases  of  the  lumbar  vertebrae.     In 


482 


THE  SPUSTAL  NERVES. 


this  condition,  the  thigh  is  strongly  flexed,  the  pelvis  tilted 
upward,  and  the  limb  shortened ;  while  passive  extension 
creates  a  deviation  of  the  body  toward  the  affected  side,  and 
is  extremely  painful. 

In  rare  instances,  tonic  and  clonic  types  of  spasm  are  ob- 
served in  the  extensor  and  adductor  muscles  of  the  thigh,  as 
the  result  of  neuralgia  of  the  knee  joint  and  certain  spas- 
modic diseases  of  a  central  origin. 

The  flexor  muscles  of  the  leg  may  be  affected  with  spasms 
in  spinal  affections,  hysteria,  diseases  of  the  knee  joint,  and 
in  inflammation  of  its  adjacent  muscles. 


Fig.  177. —  Tlic  motor  points  on  the  antcHor  aspect  of  the  thigh. 

1,  crural  nerve  ;  2,  obturator  nerve ;  3,  sartorius  muscle ;  4,  adductor  longus  muscle ;  5, 
branch  of  the  anterior  crural  nerve  for  the  quadriceps  extensor  muscle ;  6,  the  quad- 
ric  lis  muscle ;  7,  branch  of  anterior  crural  nerve  to  the  vastus  internus  muscle ;  8, 
tensor  vaginoe  femoris  muscle  (supplied  by  the  superior  gluteal  nerve);  9,  external 
cutaneous  branch  of  anterior  crural  nerve  ;  10,  rectus  femoris  muscle;  11,  1?,  vastus 
externus  muscle. 

In  rare  cases,  the  anterior  muscles  of  the  leg,  which  are 
supj)lied  by  the  peroneal  nerve,  are  affected  with  spasms  as 


PARALYSIS   OF  SCIATIC  NERVE  OR  ITS  BRANCHES,    483 

the  result  of  exposure  to  cold  or  dampness,  over-exertion  of 
the  lower  limbs,  or  paralysis  of  the  antagonistic  muscles; 
while  the  muscles  supplied  by  the  posterior  tibial  nerve,  as 
well  as  those  of  the  sole  of  the  foot,  are  more  frequently 
affected  as  the  result  of  spinal  affections,  joint  diseases,  over- 
exertion, paralysis  of  other  muscles,  and  by  the  reflex  action 
of  cholera. 


PARALYSIS   OF   MUSCLES   SUPPLIED   BY  THE   SCIATIC   KERVE   OR  ITS 

BRANCHES. 

When  we  consider  how  extensively  this  nerve  is  distrib- 
uted, and  its  exposed  situation  in  various  portions  of  its 
course,  as  w^ell  as  its  intimate  relations  to  the  organs  of  the 
pelvis,  we  can  better  appreciate  the  reasons  for  the  frequency, 
on  the  one  hand,  and  the  importance,  on  the  other,  of  the 
paralysis  which  may  affect  it  or  its  branches.  Among  the 
causes  of  this  form  of  paralysis  may  be  enumerated  all  those 
conditions  of  the  trunk  which  are  capable  of  producing  press- 
ure upon  the  origin  of  the  nerve  ;  all  forms  of  accidents  which 
may  result  in  laceration  or  section  of  the  main  trunk  or  any  of 
its  branches  ;  the  development  of  tumors  in  the  course  of  the 
nerve  ;  dislocations  of  bone ;  the  compression  of  cicatrices  ; 
rheumatic  conditions,  from  chilling  or  wetting  of  the  lower 
extremities ;  surgical  operations ;  and  spinal  diseases  which 
impair  its  point  of  origin  at  the  lumbar  enlargement  of  the 
cord. 

If  the  peroneal  nerve  be  alone  affected,  the  foot  can  not  be 
flexed  or  abducted ;  neither  can  it  be  completely  adducted. 
The  dependent  position  of  the  foot,  which  hangs  downward, 
interferes  seriously  with  the  act  of  walking,  since  the  toe 
trips  upon  every  slight  elevation. 

In  order  to  walk,  the  patient  is  compelled  to  lift  the  foot 
by  flexion  at  the  hip  joint,  and  places  it  insecurely  upon  the 
ground  with  the  outer  border  of  the  toes  first,  thus  producing 
a  gait  which  is  pathognomonic  of  this  special  type  of  paraly- 
sis. The  arch  of  the  foot  becomes  flattened  from  a  loss  of 
power  in  the  peroneus  longus  muscle  ;  the  great  toe  can  not 


484 


TEE  SPINAL  NERVES. 


be  extended,  since  the  extensor  longns  pollicis  is  paralyzed  ; 
flexion  of  the  foot  is  impaired,  since  the  extensor  communis 
digitorum  no  longer  acts ;  and  the  abduction  of  the  foot  is 
rendered  impossible,  if  the  peroneus  brevis  be  paralyzed, 
although  the  extensor  communis  digitorum  may  assist  in  this 
act  coincidentally  with  dorsal  flexion  of  the  foot. 


Fio.  178. —  TJic  motor  points  on  the  inner  aspect  of  the  kg. 

1,  intemal  head  of  gastrocnemius  muscle ;  2,  soleus  muscle ;  3,  flexor  communis  digito- 
rum muscle  ;  4,  posterior  tibial  nerve  ;  5,  abductor  pollicis  muscle. 


If  the  tlMal  nerve  be  paralyzed,  a  loss  of  power  in  the 
muscles  of  the  calf  is  indicated  by  an  inability  on  the  part  of 
the  patient  to  extend  the  foot  and  to  produce  flexion  and  a 
lateral  movement  of  the  toes.  Thi'is  the  patient  is  no  longer 
able  to  stand  upon  the  toes,  while,  in  consequence  of  a  sec- 
ondary contracture  of  the  muscles  situated  upon  the  anterior 


PARALYSIS  OF  SCIATIC  NERVE  OR  ITS  BRANCHES.    485 

surface  of  the  leg,  the  foot  is  made  to  assume  a  position  which 
has  been  compared  to  the  shape  of  a  hook.  The  tibialis  pos- 
ticus muscle  no  longer  assists  in  adducting  the  foot  and  rais- 
ing its  inner  border ;  the  flexor  communis  digitorum  can  no 
longer  flex  the  two  distal  phalanges  of  the  toe,  while  paraly- 


FiG.  I'ZQ. —  The  motor 'points  on  the  outer  aspect  of  the  leg. 
1,  peroneal  nerve ;  2,  external  head  of  gastrocnemius  muscle ;  3,  soleus  muscle ;  4,  ex- 
tensor communis  digitorum  muscle  ;  5,  peroneus  brevis  muscle ;  6,  soleus  muscle  ;  7, 
flexor  longus  pollicis  ;  8,  peroneus  longus  muscle  ;  9,  tibialis  anticus  muscle  ;  10,  ex- 
tensor longus  pollicis  muscle;  11,  extensor  brevis  digitorum  muscle;  12,  abductor 
minimi  digiti  muscle  ;  13,  deep  branch  of  the  peroneal  nerve  to  the  extensor  brevis 
digitorum  muscle  :  14,  14,  14,  dorsal  intcrossei  muscles. 


sis  of  the  flexor  longus  pollicis  deprives  the  patient  of  the 
power  of  flexing  the  great  toe.     A  lateral  motion  of  the  great 

33 


486  THE  SPINAL  NERVES. 

toe  is  no  longer  possible,  since  the  power  of  the  adductor  and 
abductor  pollicis  muscles  is  abolished,  while  paralysis  of  the 
interossei  muscles  (as  mentioned  also  in  connection  with  the 
hand)  renders  it  impossible  for  the  patient  to  flex  the  first 
phalanx,  or  extend  the  two  distal  phalanges  of  the  toes,  or 
separate  the  toes  from  each  other.  The  peculiar  position  of 
the  foot  which  results  from  this  paralysis  resembles  that  de- 
scribed in  connection  with  the  upper  extremity  as  the  "  claw 
hand,"  since  the  first  phalanx  is  abnormally  extended,  the 
second  and  third  are  strongly  flexed,  the  toes  are  tightly 
compressed  together,  and  their  bulbous  ends  no  longer  touch 
the  ground.  The  weight  of  the  body  in  a  standing  position 
is  borne  upon  the  heads  of  the  metatarsal  bones.  Hence, 
some  pain  and  inconvenience  are  experienced  after  long 
standing  or  walking. 

Paralyses  of  the  sciatic  nerve  are  accompanied,  as  a  rule, 
by  disturbances  of  the  sensibility  of  the  affected  parts.  An- 
aesthesia commonly  exists  over  the  regions  supplied  by  the 
motor  nerves  to  the  muscles  which  are  paralyzed  ;  hence,  this 
symptom  may  serve  as  a  guide,  in  some  cases,  to  the  seat  of 
the  lesion  which  has  created  the  paralysis.  In  addition  to 
these  disturbances  of  sensibility,  you  may  often  notice  changes 
in  the  circulatory  apparatus  in  the  form  of  coldness  of  the 
skin,  cyanosis,  stasis  in  the  veins,  and  a  mottling  of  the  part 
with  bluish-red  streaks. 

The  tropJiic  disturbances  which  are  commonly  met  with 
in  severe  forms  of  paralyses  of  the  peripheral  branches  of  the 
sciatic  nerve  comprise  serious  bed-sores  on  the  heels,  ankles, 
and  over  the  sacrum ;  ulceration  of  the  skin ;  eruptions  of 
herpes  and  pemphigus ;  and,  finally,  marked  atrophy  of  the 
muscles.  When  the  sciatic  nerve  is  affected  by  a  spinal  le- 
sion above  the  cauda  equina,  the  rectum  and  bladder  are  fre- 
quently completely  paralyzed. 


INDEX. 


^sthesodic  system,  313, 

systematic  lesions  of,  315. 

Ageusia,  its  tests  and  clinical  significance, 
236. 

Amaurosis,  123,  126,  144. 

Amblyopia,  49,  50,  127. 

Amyotrophic  lateral  sclerosis,  329. 

Anaesthesia,  its  significance  when  combined 
with  hemiplegia,  73. 

Anaesthesia  of  locomotor  ataxia,  320. 

Aneurismal  cough,  254. 

Angular  gyrus,  guide  to,  72. 

its  function,  50,  52. 

Anosmia,  its  causes,  and  clinical  significance, 
102. 

Aphasia,  its  relations  to  embolism,  89. 

surgical  relief  of,  73,  74. 

traumatic,  73. 

varieties  of,  and  causes,  32. 

Aqueduct  of  Fallopius,  177,  1S2. 

lesions  within,  196. 

Aqueduct  of  Sylvius,  its  special  center,  58. 

Arm,  motor  points  of  (cuts),  415,  416. 

Arnold's  nerve,  239. 

Artery,  middle  cerebral,  distribution  of,  37. 

Astigmatism,  its  tests  and  clinical  signifi- 
cance, 110,  111. 

Ataxia,  changes  of  the  pupils  in,  323. 

locomotor,  316. 

"  reflex  tests  "  of,  323,  324. 

symptoms  of,  320,  321,  322. 

tests  for,  321,  322,  323. 

Auditory  nerve,  198. 

Auditory  vertigo,  its  clinical  significance, 
211. 

Basal  ganglia,  effects  of  lesions  of,  81. 
Bell,  respiratory  nerves  of,  187. 


Bell's  paralysis,  180, 181,  191, 192, 193, 194. 

its  effect  on  smell,  102. 

its  varieties,   causes,  and  symptoms, 

192,  193,  194,  195. 

Bent  arm,  its  clinical  significance,  387. 

Bladder,  its  relations  to  focal  lesions  of  the 
spinal  cord,  345. 

Boulimia,  its  clinical  significance,  257. 

Brachial  plexus,  378. 

branches  of  inner  cord  of,  383,  384. 

branches  of  outer  cord  of,  382. 

branches  of  posterior  cord  of,  384. 

communications  of,  382. 

cords  of,  378,  379,  380. 

- —  (cuts),  379,  380. 

Brain,  its  anatomy,  functions,  and  clinical 
aspects,  19. 

clinical  subdivisions  of,  80,  81,  82. 

component  parts  of,  weight  of,  22,  23, 

24. 

convolutions  and  sulci  of,  75,  76,  77. 

effects  of  destructive  lesions  of  gray 

matter  of  (general  summary),  89. 

effects  of  diffused  lesions  of,  90. 

effects  of  effusion  into  lateral  ventri- 
cles, haemorrhage,  and  softening  of, 
38. 

effects  of  intra-cranial  pressure,  82. 

effects  of  irritative  lesions  of,  89. 

effects  of  lesion  in  the  median  line  of, 

82. 

effects  of  lesion  of  one  lateral  half  of 

(general  summary),  82. 

embolism  of,  34. 

fourth  ventricle  of,  its  nuclei,  66. 

functions  of  the  cerebellum,  61. 

function  of  cerebral  convolutions  (gen- 
eral deductions),  56. 


488 


INDEX. 


Brain,  functions  of  crura  cerebri,  59. 

functions  of  internal  capsule  of,  26,  91. 

function  of  lower  portions  of,  56. 

functions  of  medulla,  65,  66. 

functions  of  pons  Varolii,  59,  61. 

ganglia  of,  19,  20. 

general  propositions  relative  to  effects 

of  lesions  of  its  component  parts,  81. 

general   summary   of  its    physiology 

and  the  effects  of  lesions  of  its  sub- 
stance, 82,  83,  84,  85. 

gray  matter  of,  19,  20. 

growth  of,  23,  24. 

inferior  aspect  of  (cut),  22. 

in  profile  (cut),  20,  21. 

special  centers  of  motion  of  (cut),  39, 

41. 

transverse  vertical  section  of  (cut),  22. 

weight  of,  22,  24,  25. 

Broca,  center  of,  32,  33. 

center  of,  surgical  guide  to,  71. 

the  alveolo-condyloid  plane  of,  69. 

Canal,  intestinal,  effect  of  section  of  pneu- 
mogastric  upon,  253. 

Canals,  semicircular,  200,  204,  206,  207. 

semicircular,  effects  of  section  of,  215, 

216,  217,  218. 

semicircular,  their  relations  to  audi- 
tory vertigo,  215. 

Cardialgia,  257. 

Central  myelitis  of  spinal  cord,  338. 

Cerebellar  ataxia,  64. 

vertigo,  62. 

Cerebellum,  effects  of  lesions  of  (general 
summary),  82. 

functions  of,  61. 

its  numerous  connections,  63,  64. 

vertigo  and   ataxia   dependent   upon, 

63,^64,  65. 

Cerebral  thermometry,  84. 

topography,  its  surgical  beaiings,  68. 

Cerebro-spinal  axis,  5. 

fluid,  292. 

fluid,  its  normal  quantity  and  func- 
tions, 292,  293. 

fluid,  its  relation  to  consciousness,  45. 

nerves,  5-9. 

Cerebrum,  its  anatomy,  functions,  and  clini- 
cal aspects,  25. 

caudate  nucleus  of,  48. 

centers  of  motion  of,  28. 

construction  of  its  gray  matter,  75. 


Cerebrum,  converging  fibers  of,  26. 

convolutions  of  (cut),  31. 

convulsions  due  to  lesions  of,  47. 

cortex  of,  its  centers,  32. 

course  of  nerve  impulses  in  (diagram), 

53. 
effects  of  lesions  of  central  portions 

of,  92. 
effects   of  lesion   of  cortex  (general 

summary),  82. 
effects  of  lesions  of  internal  capsule 

of,  91. 
effects  of  lesions  of  motor  area  of, 

37,  38. 
effects  of  lesions  of  the  white  center 

of  the  hemispheres,  81. 

effects  of  removal  of,  29. 

excitable  regions  of  its  cortex,  85. 

frontal  lobes  of,  35. 

functions  of,  27. 

functions  of  frontal  lobes  of,  35. 

functions  of  special  motor  centers  of, 

40,  42. 

guides  to  basal  ganglia  of,  71. 

gyri  of,  77,  78,  79. 

haemorrhage  of,  its  effects  upon,  30. 

hemispheres  of,  functions  of,  28. 

internal  aspect  of  (cut),  25. 

internal  capsule  of,  26. 

irritability  of,  28. 

irritative  lesions  of  motor  area  of,  4  6. 

its  basal  ganglia,  26. 

its  convolutions,  75. 

lenticular  nucleus  of,  48. 

lobes  of,  7B. 

.lobules  of,  76. 

lobules  of,  their  situation,  79. 

motor  regions  of,  36. 

motor  and  sensory  tracts  of  (cut),  35. 

occipital  lobe  of,  its  functions,  50. 

principal  fissures  of,  77. 

results  of  lesions  of  frontal  lobe  of,  35. 

sensory  lesions  of,  48. 

sensory  regions  of  cortex  of,  86. 

softening  of,  its  effects,  30. 

special  centers  of  motion  of,  39. 

structure  of  convolutions  of  (cut),  83. 

sulci  of,  76. 

temporo- sphenoidal  lobes  of,  and  their 

functions,  51. 
Cervical  plexus  of  nerves,  364. 

deep  branches  of,  369. 

its  situation,  368. 


INDEX, 


489 


Cervical  plexus,  superficial  branches  of,  366. 
Ciieek,  hypertrophy  of,  its  causes,  163. 
Chorda  tympani  nerve,  its  relations  to  taste, 

160. 
Choreic  movements,  their  clinical  significance 

in  connection  with  cerebral  lesions, 

91. 
Choroiditis,  its  effect  on  vision,  143. 
Ciliary  muscle,  its  function  and  nerve  distri- 
bution, 129,  132,  133. 
Cilio-spinal  center,  14Y,  3?1,  311,  351. 
its  relations  to  focal  lesions  of  cord, 

343. 
Claw-hand  deformity,  330. 
Cochlea,  204,  207. 

Coitus,  its  relation  to  spinal  disease,  347. 
its  relation  to  small  sciatic  and  pudic 

nerves,  466,  468. 
Color  blindness,  116. 

Column  of  Burdach,  sclerosis  of,  315,  316. 
Column  of  GoU,  sclerosis  of,  315,  316. 
Column  of  Tiirck,  sclerosis  of,  315,  326. 
Conjunctiva,  its  nervous  supply,  physiology 

of,  171. 
Consciousness,  its  relation  to  brain  lesions, 

45. 
Convulsions  of  cerebral  origin,  47. 
Cornea,  ulceration  of,  its  relations  to  fifth 

nerve,  170. 
Corpora  quadrigemina,  effect  of  lesions,  91. 

their  functions,  58. 

Corpus  striatum,  26. 

its  functions,  54. 

subdivisions  of,  26. 

Corti,  membrane  of,  210. 

organ  of,  201,  208,  209. 

Cranial  nerves,  9-95. 

Cranium,  surgical  guides  of,  68,  69,  70,  71. 

Crural  neuralgia,  450. 

Crus  cerebri,  its  functions,  59. 

Deaf-mutism,  220. 

Defecation,  center  of ,  311. 

its  relations  to  focal  lesions  of  the  spi- 
nal cord,  345,  347,  352. 

Deglutition,  center  of,  67. 

center  of,  reflex  acts  of,  233. 

effects  of  section  of  fifth  nerve  upon, 

160. 

excitory  nerve  of,  231. 

its  relations  to  glosso-pharyngeal  nerve, 

223. 

its  relation  to  the  otic  ganglion,  174. 


Deglutition,  mechanism  of,  226,  227,  228, 

229,  230,  231,  232,  233. 

muscles  connected  with,  370. 

relations  of  hypo-glossal  nerve  to,  277. 

relations  of  spinal  accessory  nerve  to, 

264. 
Diabetes,  center  of,  67. 
Diaphragmatic  tetanus,  376. 
Digestive  tract,  effects  of  section  of  pneu- 

mogastric  nerve  upon,  251. 
Diplopia,  its  clinical  significance,  148,  149. 
Duchenne's  disease,  149-196,  234,  278,  279. 

its  relations  to  tetanoid  paralysis,  330. 

Dyspnoea,  its  relations  to  focal  lesions  of 

the  spinal  cord,  344. 

Ear,  external,  201. 

internal,  204. 

internal,  fluids  of,  205. 

middle,  201. 

relations  of  muscles  of,  to  hearing,  187. 

Earache,  its  diagnostic  importance,  171. 

its  relations  to  fifth  nerve,  170. 

Eighth  nerve  (see  Nerve,  Auditory),  198. 

Eleventh  nerve  (see  Nerve,  Spinal  Acces- 
sory), 259. 

Embolism  of  brain,  34. 

Epilepsy,  spinal,  345. 

Erection,  center  of,  311. 

Eustachian  tube,  function  of,  202. 

its  clinical  points  of  interest,  217,  218. 

Eye,  in  facial  paralysis,  190. 

its  relations  to  facial  diplegia,  197, 198. 

Eyeball,  center  of  movements  of,  139. 

motions  of,  135, 136, 137, 138, 139, 140. 

Eyelid,  effect  of  closure  of,  on  lachrymal  ap- 
paratus, 121. 

mechanism  of  its  closure,  121. 

Eyes,  bilateral  deviation  of,  in  cerebral  le- 
sions, 40. . 

oscillatory  movements  of,  their  clinical 

significance,  215. 

Face,  in  facial  diplegia,  197. 

motor  centers  of,  42,  43. 

motor  points  of  (cut),  282. 

paralysis  of  muscles  of,  191,  192,  193, 

194. 

relations  of  cervical  plexus  to  expres- 
sion of,  368. 

relation  of  facial  nerve  to  expression 

of,  189. 

spasm  of  muscles  of,  190,  191. 


490 


INDEX. 


racial  diplej^ia,  196,  197. 

Facial  nerve  (see  Nerve,  Facial),  177. 

function  of  chorda  tympani  branch  of, 

IGO. 
Facial  neuralgia,  IGl. 
Fallopius,  aqueduct  of,  177,  182. 
aqueduct  of,  its  relations  to  facial  pa- 
ralysis, 193,  194. 
Fascia  of  chest,  nerve  distribution  of,  368. 

of  forearm,  its  nerve  supply,  388. 

of  leg,  its  relation  to  cutaneous  nerves, 

474. 

its  nervous  supply,  447. 

Fasciae,   nervous    distribution    to   (general 

axiom),  12,  13. 
Fibers  of  Remak,  9. 
Fifth  cranial  nerve  (see  Nerve,  Trigeminus), 

151. 
First  cranial  nerve  (see  Nerve,  Olfactory),  95. 
Fissure,  calcarine,  of  cerebrum,  80. 

calloso-marginal,  of  cerebrum,  80. 

external  parieto-occipital,  its  relations 

to  the  lambdoidal  suture,  68. 
external  parieto-occipital,  its  eituation, 

77. 
external     parieto  -  occipital,    surgical 

guide  to,  71. 
internal  parieto-occipital,  of  cerebrum, 

80. 

of  Rolando,  37,  42. 

guide  to,  70,  72. 

its  relation  to  the  coronal  suture,  68. 

its  situation,  77. 

of  Sylvius,  guides  to,  71,  72. 

its  situation,  77. 

its  surgical  importance,  77. 

Foot,  its  attitude  in  tibial  paralysis,  485,  486. 
Forearm,  motor  points  of  (cut),  417,  418. 
Fourth  cranial  nerve  (see  Nerve,  Trochlea- 

ris),  149. 
Fremitus  of  fingers  in  paralytic  dementia, 

281. 

Gait  of  locomotor  ataxia,  321. 

of  peroneal  paralysis,  483,  484. 

of  sciatic  paralysis,  481. 

of  tetanoid  paraplegia,  330. 

Ganglion,  ciliary,  174,  175. 

jugular,  222. 

jugular,  of  pneumogastric,  239. 

lenticular,  174,  175. 

Meckel's,  174,  175,  183,  186. 

Meckel's,  excision  of,  173. 


Ganglion,  of  Luschka,  372. 

of  root  of  pneumogastric,  239. 

of  trunk  of  pneumogastric,  239. 

ophthalmic,  174,  175. 

ophthalmic,  its  relation  to  sixth  nerve, 

176. 

otic,  174,  175,  183,  186. 

submaxillary,  174,  175. 

of  Andersch,  222, 

of  Gasser,  229. 

Ganglia,  basal,  of  cerebrum,  26. 

basal,  of  cerebrum,  effects  of  destruc- 
tion of,  56,  57. 

basal,  of  cerebrum,  effects  of  lesions 

of,  81. 

basal,  of  cerebrum,  their  functions,  54. 

connected  with  fifth  cranial  nerve,  173, 

174. 

of  the  brain,  19,  20. 

— -  of  the  fifth  nerve  (table  of),  175. 

General  axioms  of  nerve  distribution,  11, 
12,  13. 

Genito-urinary  center,  301,  311. 

Glands,  cervical,  relations  of  their  enlarge- 
ment to  fifth  nerve,  170. 

Globus  hystericus,  254. 

Glossoplegia,  278,  279. 

Glottis,  respiratory  movements  of,  264. 

Gluteal  paralysis,  461. 

Gubler,  line  of,  183,  192. 

Hair,  sudden  blanching  of,  169. 

Hand,  its  relation  to  paralysis  of    median 

nerve,  397. 
its  relation  to  paralysis  of  musculo- 

spiral  nerve,  415,  416. 
its  relation  to  paralysis  of  ulnar  nerve, 

403,  404. 

motor  centers  of,  43. 

motor  points  of  (cut),  417,  418. 

Handwriting,  its  modifications  in  paralytic 

dementia,  281. 
Head,  nerve  supply  to  posterior  portion  of,! 

366,  367. 
Hearing,  centers  of,  86. 
effects  of  section  of  fifth  nerve  upon, 

160. 

general  view  of  organ  of,  200. 

its  relations  to  facial  paralysis,  194. 

its  relation  to  otic  ganglion,  174. 

I mechanism  of,  202,  203,  204,  207,  208, 

I  209,  210. 

I relations  of  muscles  of  ear  to,  187. 


INDEX, 


491 


Hearing,  special  centers  of,  52. 

Heart,  acceleratory  center  of,  342,  343,  344. 

effects   of    section   of  pneumogastric 

upon,  251. 

inhibitory  center  of,  67. 

Hemianopsia,  its  varieties  and  causes,  123, 
124. 

Hemiparaplegia,  348,  352. 

Hemiplegia  spinal,  348,  350. 

Hiccough,  374,  375. 

its  relations  to  focal  lesions  of  spinal 

cord,  343. 

Huguier,  canal  of,  182. 

Hypergeusia,  its  tests  and  clinical  signifi- 
cance, 235. 

Hyperopia,  its  effects  on  health,  109,  110. 

Hyperosmia,  its  causes  and  tests,  102. 

Incoordination,  theories  of  origin  of,  325. 

Intercostal  neuralgia,  430. 

Internal  capsule  of  the  brain,  26,  48. 

effects  of  lesions  of,  44,  49,  91. 

Iris,  its  nervous  supply  and  movements,  130, 
131,  134,  135. 

reflex  action  of,  and  its  clinical  bear- 
ings, 135. 

relations  of  blood-vessels  to  move- 
ments, 134. 

Island  of  Keil,  effects  of  lesions  of,  86. 

its  situation,  79,  80. 

Jacksonian  epilepsy,  47. 

Kinesodic  system,  313. 
Kopp's  asthma,  254. 

Labyrinth,  its  anatomy  and  functions,  204. 
Lachrymal  apparatus,  its  relation  to  facial 

paralysis,  198. 
Larynx,  effects  of  section  of  pneumogastric 

nerve  upon,  249. 
Lenticular  nucleus,  48. 
Liver,  effects  of  section  of  pneumogastric 

nerve  upon,  252. 
Lobe,  frontal,  of  cerebrum,  35. 
frontal,  of  cerebrum,  fifth  convolution 

of,  in  criminals,  77. 
frontal,  of  cerebrum,  its  convolutions 

or  gyri,  78. 
occipital,  of  cerebrum,  its  convolutions 

or  gyri,  79. 
occipital,  of  cerebrum,  its  functions, 

50. 


Lobe,  parietal,  of  the  cerebrum,  its  convo- 
lutions or  gyri,  78. 

Lobule,  occipital,  its  situation,  80. 

para-central,  37. 

its  situation,  80. 

Lobulus  centralis,  its  situation,  79. 

quadratus,  its  situation,  80. 

Local  tenderness  of  skin,  significance  of,  12. 

Locomotor  ataxia,  316. 

Locus  cseruleus,  175. 

Lower  extremity,  motor  centers  of,  40,  42. 

Lumbar  plexus,  435,  436. 

tables  of  branches  of,  437,  438. 

Lumbo-sacral  cord,  458. 

Lungs,  effect  of  section  of  pneumogastric 
nerve  upon,  250. 

Macropsia,  its  clinical  significance,  142,  143. 

Macula  lutca,  105. 

Malum  Cotunnii,  478. 

Mastication,  effects  of  section  of  fifth  nerve 

upon,  160. 
its  alteration  in  Duchenne's  disease, 

279. 
Mastodynia,  432,  433. 
Meckel's  ganglion,  174,  175. 
Median  nerve,  trophic  effects  of  paralysis 

of,  398. 
Medulla  oblongata,  respiratory  center  of,  its 

clinical  relations,  342. 

centers  of,  and  their  functions,  66,  67. 

functions  of,  65. 

nerve,  nuclei  of,  66. 

Mcgalopsia,   its   clinical    significance,    142, 

143. 
Meniere's  disease,  62,  120,  211. 
Meningo-encephalitis,  90. 
Meso-cephalon,  motor  and  sensory  tracts  of 

(cut),  35. 
Micropsia,  its  clinical  significance,  142,  143. 
Micturition,  center  of,  311. 
its  relations  to  focal   lesions  of  the 

spinal  cord,  345,  347,  352. 
Monoplegia,  surgical  relief  of,  74. 

traumatic  and  surgical  aspects,  74. 

types  of,  45,  46. 

Motor  nerves,  methods  of  termination  (cut), 

10. 
Motor  oculi  nerve,  127. 

its  clinical  relations,  142. 

its  origin  and  course,  127,  128. 

its  relations  to  the  perception  of  dis- 
tance, 140. 


492 


INDEX. 


Motor  oculi  nerve,  physiology  of  its  distri- 
bution, 131,  132,  133. 

symptoms  of  paralysis  of,  145. 

Motor  points  of  upper  extremity  (cut),  416, 
416,  417,  418. 

Mouth,  changes  due  to  spasm  of,  165. 

changes  in  Bell's  paralysis,  180. 

motor  centers  of,  42. 

Muscae  volitantes,  their  causes,  115. 

Muscle,  buccinator,  its  relations  to  degluti- 
tion, 227. 

buccinator,  physiology  of  action,  188, 

189. 

platysma,   physiology    of  its    action, 

188. 

quadriceps  extensor,  spasm  of,  448. 

stapedius,  181. 

stapedius,  function  of,  217. 

sterno-mastoid,  its  nerve  supply,  266. 

sterno-mastoid,  paralysis  of,  270,  271. 

sterno-mastoid,  tonic  and  clonic  spasm 

of,  268,  269. 

tensor  tympani,  function  of,  204,  217. 

tensor  tympani,  its  relations  to  facial 

paralysis,  194. 

trapezius,  its  nerve  supply,  266. 

trapezius,  paralysis  of,  271,  272. 

trapezius,  tonic  and  clonic  spasm  of, 

268,  269. 

Muscles,  causes  of  contracture  after  paraly- 
sis of,  346. 

extensor  and  adductor  groups  of  thigh, 

spasm  of,  482. 

flexor  group  of  foot,  spasms  of,  482, 

483. 

flexor  group  of  leg,  spasm  of,  482. 

gluteal,  paralysis  of,  461,  462. 

gluteal,  spasms  of,  461. 

of  the  hip,  spasm  of,  452,  481. 

of  the  thigh,  atrophy  of,  450. 

of  the  thigh  and  leg,  their  physiological 

groupings,  454,  455. 

of  voice,  nervous  supply  of,  263. 

Jlyelitis,  central,  of  spinal  cord,  338. 

of  anterior  horns  of  spinal  cord,  331. 

polio-,  332. 

Myopia,  its  cjffects,  109,  111. 

Nerve,  abducens,  175,  176. 

abducens,   clinical   relations   of,    176, 

177. 

abducens,  functions  of,  176,  177. 

accessory  obturator,  437,  438. 


Nerve,  accessory  obturator,  its  distributions 
and  functions,  456,  457. 

anterior  crural,  437,  438. 

anterior  crural,  its  clinical  relations, 

447. 

anterior  crural,  its  distributions  and 

functions,  444,  445. 

anterior  crural,  its  relations  to  joints, 

444,  445. 

anterior  interosseous,  382. 

anterior  tibial,  472. 

Arnold's,  239. 

auditory,  198. 

auditory,  anasthesia  of,  220. 

auditory,  clinical  points  afforded  by, 

211. 

auditory,  diagram  of,  198. 

auditory,  hyperaesthesia  of,  219. 

auditory,  its  origin,  198. 

— —  auditory,  peculiarity  of  fibers  of,  199. 

cardiac,  245. 

cervical,  clinical  points  pertaining  to, 

372. 

cervico-facial,  179.  182,  188. 

chorda  tympani,  182,  183,  234. 

chorda  tympani,  diagram  of,  183,  185. 

chorda  tympani,  function  of,  225. 

chorda  tympani,  its  origin,  179. 

chorda  tympani,  its  relations  to  facial 

paralysis,  193,  194. 

chorda  tympani,  its  relation  to  the  sub- 
maxillary gland,  174. 

chorda  tympani,  its  relations  to  taste, 

160. 

ciliary,  153,  154. 

circumflex,  of  arm,  378,  384,  406. 

circumflex,  of  arm,  its  clinical  rela- 
tions, 407. 

circumflex,  of  arm,  its  distribution  and 

functions,  406,  407. 

cochlear,  200. 

communicans  noni,  275,  276,  362,  364. 

communicans  noni,  its  surgical  rela- 
tions, 369. 

compound,  of  the  head,  172. 

cutaneous,  of  ear,  158. 

dental,  inferior,  153,  154. 

depressor,  of   heart,    238,    239,  245, 

263. 

depressor,   of  heart,  its   relations  to 

spinal  accessory  nerve,  265. 

dcscendcns  noni,  275,  276. 

dorsal,  of  penis,  459. 


INDEX. 


493 


Nerve,  dorsal,  of  penis,  its  distributions  and 
functions,  467,  468. 

efferent,  7. 

excitory,  of  deglutition,  231. 

external  anterior  thoracic,   378,   382, 

t385. 
external  cutaneous,  of  the  arm,  378, 
382,  385. 
external  cutaneous,  of  the  thigh,  437, 
438. 
external  cutaneous,  of  thigh,  its  distri- 
bution and  functions,  442,  443. 

external  popliteal,  459,  472. 

external  respiratory,  of  Bell,  378. 

external  saphenous,  472. 

facial,  177. 

facial,    clinical    points    afforded    by, 

190. 

facial,  communications  of,  178,  179. 

facial,  course  of,  177. 

facial,  diagram  of,  179. 

facial,  functions  of,  179,  180. 

facial,  lingual  branch  of,  182,  184. 

facial,  its  relations  to  Duchenne's  dis- 
ease, 280. 

facial,  origins  of,  177. 

facial,  paralysis  of,  180. 

facial,  relations  to  fifth  nerve,  183. 

facial,  table  of  branches  of,  182. 

fibers  (cut),  5. 

frontal,  153,  154. 

genito-crural,  437,  438. 

genito-crural,  its  distribution  and  clini- 
cal relations,  443,  444. 

glosso-pharyngeal,  220. 

glosso-pharyngeal,    clinical   points   of 

interest  of,  234. 

glosso-pharyngeal,  effects  of  section  of, 

225. 

glosso-pharyngeal,  its  origin  and  rela- 
tions, 221. 

glosso-pharyngeal,  table  of  branches 

of,  225. 

great  auricular,   362,  363,    364,    366, 

367. 

great  occipital,  362,  363,  366,  367. 

great  sciatic,  458,  459. 

great  splanchnic,  its  relation  to  pain, 

426. 

gustatory,  153,  154. 

hypo-glossal,  272. 

hypo-glossal,  clinical  points  pertaining 

to,  277. 


Nerve,  hypo-glossal,  communications  of,  273, 

274,  275. 

hypo-glossal,  effects  of  section  of,  277. 

hypo-glossal,  general  function  of,  272, 

276. 
hypo-glossal,  its   relations   to  degluti- 
tion, 227,  228,  277. 

hypo-glossal,  origin  of,  272,  273. 

ilio-hypogastric,  437,  438. 

ilio-hypogastric,  its  clinical  relations, 

440. 
iliohypogastric,  its  distributions  and 

functions,  439,  440.^ 

ilio-inguinal,  437,  438. 

ilio-inguinal,  its  clinical  relations,  440. 

ilio-inguinal,  its  distribution  and  func- 
tions, 439,  440. 
inferior  dental,  rules  for  section  of, 

173. 

inferior  gluteal,  459. 

inferior  hemorrhoidal,  459. 

inferior  hemorrhoidal,  its  distributions 

and  functions,  467,  468. 

inferior  maxillary,  153,  154. 

inferior  pudendal,  459. 

inhibitory,  of  vaso-motor  center,  247. 

intercostal,  physiology   of,  421,  422, 

423,  424. 
internal  anterior  thoracic,    378,    383, 

385. 
internal  cutaneous,  of  arm,  378,  383, 

398. 

internal  cutaneous,  of  the  thigh,  438. 

internal  popliteal,  459,  472. 

internal  saphenous,  438. 

Jacobson's,  225. 

lachrymal,  153,  154. 

laryngeal,  242,  243. 

lesser  internal  cutaneous,   378,   383, 

398. 

long  saphenous,  438. 

long   saphenous,  its  distribution  and 

physiology,  447. 

median,  378,  382,  391. 

median,  its  clinical  relations,  395. 

median,  its  distribution  and  functions, 

393,  395. 

median,  its  surgical  relations,  393,  398. 

middle  cutaneous,  of  the  thigh,  438. 

motor-oculi,  127. 

motor-oculi  externus,  175,  176. 

muscular,  of  brachial  plexus,  378. 

musculo-cutancous,  382,385. 


494 


INDEX. 


Nerve,  musculo-cutaneous,  of  arm,  its  clinical 
relations,  390,  391. 

musculo-cutaneous,  of  arm,  its  physio- 
logical relations,  386,  387,  388. 

musculo-cutaneous,  of  leg,  472. 

musculo-spiral,  378,  384,  408. 

musculo-spiral,   its   clinical   relations, 

412. 

musculo-spiral,  its  course  and  distri- 
bution, 4<j8. 

musculo-spiral,  its  cutaneous  distribu- 
tion, 411,  412. 

mylo-hyoid,  153,  154. 

nasal,  153,  154. 

obturator,  437,  438. 

obturator,  its  clinical  relations,  455. 

obturator,  its  distributions  and  func- 
tions, 452,  453,  454. 

olfactory,  95. 

olfactory,  distribution   and   functions 

in  animals,  98. 

olfactory,  its  clinical  relations,  101. 

olfactory,  its  origin,  95,  96. 

olfactory,  its  relation  to  reflex  action, 

100. 

olfactory,  structure  of  filaments  of,  97. 

ophthalmic,  153,  154. 

optic,  103. 

optic,   causes   of    impairment  of    its 

fibers,  123,  124,  126,  126,  127. 

optic,  chiasm  of,  103. 

optic,  distribution  of,  105. 

optic,  fibers  of,  103,  104. 

optic,  its  association  with  fifth  nerve, 

106. 

optic,  its  clinical  relations,  122. 

optic,   its    effect  on  coordination  of 

movement,  120. 

optic,  its  effect  on  lachrymal  appa- 
ratus, 120. 

optic,  its  effect  on  the  pupil,  106. 

optic,  its  relations  in  the  orbit,  108. 

optic,  its   relations   to  blood-vessels, 

103,  109. 

optic,  its  clinical  relations  to  intra- 
cerebral pressure,  123. 

optic,  its  relations  to  reflex  action,  lOG. 

optic,  physiological  reasons  for  pe- 
culiar distribution  of  its  fibers,  107, 
108. 

orbital,  153,  154. 

of  Wrisberg,  199,  378,  383,  424. 

pathcticus,  149. 


Nerve,  perineal,  459. 

perineal,  its  distributions   and   func- 
tions, 467,  468. 

peroneal,  472. 

phrenic,  362,  364,  378. 

phrenic,  disorders  of,  374. 

phrenic,  its  relations  to  focal  lesion  of 

spinal  cord,  342. 

phrenic,    its    surgical    relations    and 

functions,  370. 

phrenic,  physiology  of  distribution  of, 

370,  371,  372. 

pneumogastric,  236. 

pneumogastric,  afferent  fibers  of,  247. 

pneumogastric,  anastomoses  of,  237. 

pneumogastric,  branches  of,  240. 

pneumogastric,  clinical  points  pertain- 
ing to,  253. 

pneumogastric,  course  and  relations  of, 

I  248,  249. 

I  pneumogastric,  diagram  of,  238,  241. 

I  pneumogastric,  effects  of  section  of, 

249,  250,  251,  252. 

pneumogastric,  efferent  fibers  of,  240. 

pneumogastric,  functions  of,  240. 

pneumogastric,   its   relations   to    Du- 

j  chenne's  disease,  280. 

j  pneumogastric,  relations   to  respira- 

I  tion,  247. 

j  portio  intermedia,  179. 

I  posterior  interosseous,  384,  410. 

posterior  thoracic,  378. 

posterior  tibial,  472. 

pudic,  458,  459. 

pudic,  its  clinical  relations,  468. 

pudic,  its  distributions  and  functions, 

467,  468. 

pudic,  its  relations  to  the  uiinary  or- 
gans and  coitus,  468,  469. 

pulmonary,  their  clinical  relations,  255. 

radial,  384,  410. 

recurrent  laryngeal,  239. 

sciatic,  its  clinical  relations  and  those 

of  its  branches,  478. 

sciatic,  its  distributions  and  functions, 

469,470,471. 

sciatic,  paralysis  of,  or  of  its  branches, 

483,  484. 

small   occipital,    362,    363,  364,  366, 

367. 

small  sciatic,  458,  459. 

small  sciatic,  its  distribution  and  func- 
tion, 464. 


INDEX. 


495 


Nerve,  small  sciatic,  its  relation  to  coitus, 
465,  466. 

small  sciatic,  its  relations  to  genital 

organs,  466. 

spheno-palatine,  153,  154. 

spinal  accessory,  259, 

spinal  accessory,  clinical  points  per- 
taining to,  268. 

spinal  accessory,  communications  of, 

260. 

spinal  accessory,  distribution  of,  261. 

spinal  accessory,  effects  of  extirpation 

of,  265. 

spinal   accessory,    its    communication 

with  the  suboccipital  nerve,  and  its 
physiological  importance,  267. 

spinal    accessory,   its   distribution    to 

muscles,  and  its  physiological  impor- 
tance, 266. 

spinal  accessory,  its  relations  to  deglu- 
tition, 264. 

spinal  accessory,  its  relations  to  Du- 

chenne's  disease,  280. 

spinal  accessory,  its  relations  to  the 

heart's  action,  264. 

spinal  accessory,  its  relations  to  sing- 
ing, 266. 

spinal  accessory,  its  relation  to  voice, 

264. 

sublingual,  272. 

suboccipital,  362,  366. 

subscapular,  378,  384,  404. 

supra-clavicular,  362,  363 

superficial  cervical,  362,  363,  364. 

superficial  perineal,  459. 

superior  gluteal,  458,  459. 

superior  gluteal,  its  clinical  relations, 

460,  461. 

superior  gluteal,  its  distribution  and 

functions,  459,  460. 

superior  maxillary,  153,  154. 

superior  respiratory,  of  Bell,  243. 

sympathetic,  7. 

sympathetic,  communications  of,  9. 

sympathetic,  distribution  of,  7. 

sympathetic,  function  of,  7. 

sympathetic  (cuts),  6-8. 

temporal,  deep,  153,  157. 

temporo-facial,  179,  182,  188. 

temporo-malar,  153,  154. 

thoracic,  385. 

trigeminus,  151. 

trigeminus,  afferent  fibers  of,  157. 


Nerve,  trigeminus,  clinical  points  afforded 

by,  161. 

trigeminus,  diagnostic  value  oF,  169. 

trigem.inus,  diagram  of,  154. 

trigeminus,  effects  of  section  of,  159. 

trigeminus,  efferent  fibers  of,  155. 

trigeminus,   function   of    its   efferent 

fibers,  155,  150. 
trigeminus,    ganglia    connected   with, 

173. 
trigeminus,  its  relations  to  deglutition, 

228. 
trigeminus,  its  motor  and  sensory  root, 

152. 

trigeminus,  its  origin,  151. 

trigeminus,  neuralgias   of,    161,    162, 

163. 
trigeminus,  paralysis  of,  165, 166,  167, 

168,  169. 

trigeminus,  spasms  due  to,  164. 

trigeminus,  surgical  anatomy  of,  172. 

trigeminus,  table  of  branches  of,  153. 

trochlear,  149. 

trochlear,  effect  of  paralysis  of,  150, 

151. 
trochlear,  its  origin  and  function,  149, 

150. 

tympanic,  179,  182. 

ulnar,  378,  383,  400. 

ulnar,  its  clinical  relations,  402. 

ulnar,  its  distribution,  400,  402. 

ulnar,  its  relations  to  focal  lesions  of 

cord,  344. 

ulnar,  its  surgical  relations,  400. 

vestibular,  200. 

Vidian,  182,  183,  186. 

Nerves,  afferent,  7. 

auriculo-teraporal,  153,  154. 

brachial  plexus  of,  378. 

cranial,  9-95. 

cardiac,  their  clinical  relations,  256. 

cardiac  functions  of,  245,  246. 

cerebro-spinal,  5-9. 

cervical,  355. 

cervical  (lower),  378. 

cervical,  classification  of  branches,  362. 

cervical  plexus  of,  364. 

coccygeal,  356. 

cutaneous,  clinical  guides  to,  158,  159. 

cutaneous,  of  abdomen,  their  clinical 

subdivisions,  440. 

cutaneous,  of  head,  157,  158,  159. 

dental,  anterior  and  posterior,  153, 154. 


496 


INDEX. 


Nerves,  dorsal,  355,  419,  420. 

dorsal,  their  clinical  relations,  424. 

dorsal,  their  communication  with  the 

sympathetic  nerve,  419. 

dorsal,  their  relation  to  the  brachial 

plexus,  419. 

dorsal,  their  relation  to  the  contents 

of  the  mediastinae  of  the  chest,  425. 

dorsal,  their  relation  to  heart  disease, 

424. 

dorsal,  their  relation  to  pleurisy,  424. 

dorsal,  paralysis  of,  433,  434,  435. 

dorso-lumbar,  422. 

from  lower  cervical  region,  377. 

gastric,  their  clinical  relations,  257. 

general  axioms  of,  11,  12,  13. 

hepatic  of  pneumogastric,  their  clini- 
cal relations,  258. 

intercostal,  420. 

intercostal,  lateral  and  anterior  cuta- 

neous  branches  of,  420. 

intercostal,  neuralgia  of,  430,  431,  432. 

intercostal,  their  relation  to  abdominal 

pain,  427,  428. 

intercostal,  their  relation  to  disease  of 

the  digestive  viscera,  426. 
—  intercostal,  their  relation  to  disease  of 
the  stomach,  426. 

intercostal,  their  relations  to  focal  le- 
sions of  spinal  cord,  351. 

intercostal,  their  relations  to  the  pleu- 
ra, 422. 

intestinal,  of  pneumogastric,  their  clin- 
ical relations,  258. 

laryngeal,  their  clinical  relations,  254. 

law  of  distribution  of,  10. 

lumbar,  355,  436. 

motor,  methods  of  termination  (cut), 

10. 

motor  points  of,  on  skin,  3. 

oesophageal,  251. 

of  arm  and  forearm  (tables  of),  382. 

of  hip  joint,  477,  478. 

of  larynx,  243,  244. 

of  leg  and  foot  (table  of),  472. 

of  respiratory  movements  of   glottis, 

243. 

petrosal,  179,  182,  183,  184,  186. 

petrosal,  diagram  of,  186. 

petrosal,  their  relations  to  facial  pa- 
ralysis, 193,  194. 

plantar,  472. 

practical  interest  of,  8. 


Nerves,  resection  of,  rules  for,  172. 

respiratory,  of  Bell,  187. 

sacral,  355,  457. 

sacral,  neuralj^ia  of  posterior  branclu 

of,  480. 

spinal,  9-292. 

spinal,  axioms  of  distribution  of,  358, 

359,  360. 

spinal,  roots  of,  9. 

subscapular,  distribution  of  each,  404. 

subscapular,   their   clinical    relations. 

405,  406. 

superior  maxillary,  rules  for  excision 

of,  173. 

supra-orbital,  153,  154. 

supra-orbital,   rules    for    division  .of, 

172,  173. 

supra-scapular,  378. 

thoracic  intercostal,  420. 

■ thoracico-abdominal  intercostal,  420. 

to  the  peritoneum,  and  their  physiol- 
ogy, 441. 

trochlear,  153,  154. 

vaso-motor  for  trunk,  extremity,  and 

viscera,  310. 

vaso-motor  of  spinal  cord,  310. 

Nervous  system  of  man,  general   arrange- 
ment of,  5. 

Neuralgia,  cervico-occipital,  373. 

diaphragmatic,  374. 

intercostal,  430,  431,  432. 

of  anterior  crural  nerve,  450. 

of  the  ilio-hypogastric  and  ilio-ingui- 

nal  nerves,  439,  440. 

of  the  mammary  gland,  432. 

of  the  obturator  nerve,  455. 

of  the  phrenic  nerve,  374. 

of  the  phrenic  nerve,  its  differential 

diagnosis,  375. 

of  the  sciatic   nerve,  478.  479,  480, 

481. 

Ninth  nerve,  220. 

Nucleus  caudatus,  guide  to,  71. 

Nystagmus,  its  clinical  significance,  146. 

Obturator  neuralgia,  455,  456. 

paralysis,  456. 

Ocular  movements,  center  of,  40,  52,  58. 
(Esophagus,  center  of  movement  of,  07. 
Olfactory  nerve.     (See  Nerve,  Olfactory.) 
Optic  nerve.     (See  Nerve,  Optic.) 
Optic  thalamus,  26,  48. 
guide  to,  71. 


INDEX. 


49Y 


Optic  thalamus,  its  effects  on  vision,  57. 
its  functions,  54. 

Pain,  at  knee  joint,  its  clinical  significance, 
448,  454,  474,  475,  476. 

facial,  of  Fothergill,  161. 

general  clinical  significance  of,  13. 

in  the  back,  its  relation  to  aneurism, 

427. 

in  the  pectoral  region,  its  clinical  sig- 
nificance, 427. 

in  the  penis,its  clinical  significance,466, 

in  the  pit  of  the  stomach,  its  clinical 

significance,  426. 

in  the  region  of  the  thorax,  its  diag- 
nostic value,  424,  425,  426. 

in  the  shoulder,  its  relation  to  diseases 

of  the  liver,  428. 

in  the  thorax,  its  relation  to  gastric 

and  intestinal  disease  and  tumors  of 
the  viscera,  428. 

its  relation  to  brain  lesions,  45. 

its  relation  to  the  phrenic  nerve,  371. 

of  gout,  318. 

of  locomotor  ataxia,  its  diagnostic  pe- 
culiarities, 317. 

of  rheumatism  of  muscles,  319. 

superficial,  clinical  significance  of,  11. 

Palate,  its  relation  to  deglutition,  231. 

its  relations  to  facial  paralysis,  194. 

its  relations  to  glosso-pharyngeal  nerve, 

222. 

nerves  of,  185. 

Papilla  of  retina,  105. 

Para-central  lobule,  effect  of  lesions  of,  44. 

Paralysis,  atrophic  spinal,  331. 

bilateral,  of  face,  196. 

bulbar,  278,  279. 

cerebral,  surgical  relief  of,  73,  74. 

crossed,  177,  182,  192. 

crossed,  diagram  of,  60. 

crossed,  its  varieties,  59. 

due  to  crutches,  419. 

due  to  lead  poisoning,  413,  414,  415. 

facial,  191,  192,  193,  194. 

facial  crossed,  182,  183,  184,  192, 193. 

general,  of  the  insane,  90. 

glosso-labio-laryngeal,  234,  278,  279. 

motor,  due  to  lesions  of  cortex,  44. 

motor,  its  clinical    significance  when 

occurring  on  the  same  side  as  an  in- 
jury to  the  head,  73. 

of  anterior  crural  nerve,  449,  4"30. 


Paralysis,  of  Bell,  180,  181. 

of  circumflex  nerve  of  shoulder,  407, 

408. 

of  cranial  nerves  following  injury  to 

the  head,  73. 

of  diaphragm,  374,  376. 

of  dorsal  nerves,  433,  434,  435. 

of  Duchenne,  198,  278,  279. 

of  facial  muscles,  88. 

of  facial  nerve,  its  relation  to  hemi- 
plegia, 69. 

of  the  insane,  281. 

of  lower  extremity,  88. 

of  median  nerve,  395,  396,  397. 

of  muscles  of  the  back,  434,  435,  436. 

of  musculo-cutaneous  nerve,  390. 

of  musculo-spiral  nerve,  412,  413,  414, 

415,  416. 

of  obturator  nerve,  455,  456. 

of  ocular  muscles,  its  causes,  147,  148. 

of  the  ocular  muscles,  its  effect  on  the 

position  of  the  head,  140,  141,  142. 

of  peroneal  nerve,  483. 

of  sciatic  nerve,  481,  483. 

of  sciatic  nerve,  its  sensory  disturb- 
ances, 486. 

of  sciatic  nerve,  its  trophic  disturb- 
ances, 486. 

of  superior  gluteal  nerve,  461. 

of  ulnar  nerve,  402,  403,  404. 

spastic  spinal,  329. 

of  tibial  nerve,  484,  485. 

of  tongue,  283. 

of  upper  extremity,  88. 

tetanoid,  329. 

tetanoid,  gait  of,  330. 

tetanoid,  its  relations   to  Duchenne's 

disease,  330. 

Paralytic  dementia,  281. 

Paralyzed  muscles,  early  rigidity  of,  in  cor- 
tical lesions  of  the  brain,  45. 

late  rigidity  of,  44, 

late  rigidity  of,  its  causes,  89. 

theories  of  late  rigidity  of,  48. 

Paraplegia,  hemi-,  348,  352. 

tetanoid,  329. 

Parturition,  center  of,  311. 

Patheticus  nerve,  149. 

Pleurodynia,  its  diagnosis  from  pleurisy  and 
angina  pectoris,  432. 

Point  apophysaire,  163. 

Polio-myelitis,  its  causes,  varieties,  and 
symptoms,  332,  333,  334. 


498 


INDEX. 


Polydipsia,  its  clinical  significance,  257. 

Polyphagia,  its  clinical  significance,  258. 

Pons  Varolii,  its  functions,  59,  61. 

Progressive  muscular  atrophy,  334. 

Prosopalgia,  its  clinical  significance,  161. 

Ptosis,  145. 

Puncta  dolorosa,  of  cervico-occipital  neural- 
gia, 373. 

of  crural  nerve,  450. 

of  fifth  nerve,  163. 

of  intercostal  nerve,  432. 

of  lumbar  nerves,  440. 

of  phrenic  neuralgia,  374. 

of  sciatic  nerve,  480. 

Pupil,  changes  in  and  their  physiology,  114. 

mechanism  of  its  contraction  and  dila- 
tation, 130,  131,  134,  135. 

Remak,  fibers  of,  9. 
Respiration,  center  of,  342. 
Retina,  blind  spot  of,  1 1 5. 

construction  of,  117. 

papilla  of,  Ki5. 

Rolando,  fissure  of,  37,  42. 
Roots  of  spinal  nerves,  9. 

Saccule  of  the  labyrinth,  200,  206. 

Sacral  plexus,  457. 

articular  branches  of,  458,  459, 

muscular  branches  of,  458,  459. 

muscular  branches  of,  their  distribu- 
tion and  function,  462,  463,  464. 

table  of  its  branches,  458. 

Salaam  convulsions  of  Xewnham,  270. 

Salivary  secretion,  center  of,  67. 

effects  of  section  of  fifth  nerve  upon, 

160. 

Scalp,  pain  of,  its  diagnostic  importance,  171. 

Sciatic  neuralgia,  478,  479,  480,  481. 

Second  cranial  nerve,  103. 

Sensory  impressions,  perception  of,  48. 

Seventh  cranial  nerve  (see  N"erve,  Facial),  177. 

Sight,  center  of,  60,  51,  52. 

effects  of  section  of  fifth  nerve  upon, 

160. 

Singing,  its  alteration  in  Duchcnne's  disease, 
280. 

relations  of  spinal  accessory  nerve  to, 

266. 

Sixth  cranial  nerve  (see  Nerve,  Abducens), 
175. 

Skin,  nervous  distribution  to  (general  axi- 
om), 12. 


Smell,  effect  of  fifth  nerve  upon,  98. 

effects  of  section  of  fifth  nerve  upon, 

160. 

its  modifications  and  their  causes,  99. 

its  alterations  in  Bell's  paralysis,  102. 

its  modifications  in  animals  and  races, 

98. 

its  relations  to  taste,  101. 

physiology  of  its  production,  98. 

relations  of  act  of  sniffing  to,  187. 

relations  of  the  facial  nerve  to,  187. 

special  centers  of,  52,  53. 

tests  for,  101,  102. 

Sneezing,  its  physiology,  99. 

Sommering,  yellow  spot  of,  105. 

Spasm  of  diaphragm,  due  to  phrenic  nerve, 

374,  376. 

of  gluteal  muscles,  461. 

of  lower  limbs,  481. 

of  muscles  of  the  hip,  452. 

of  quadriceps  extensor  muscle,  448. 

of  sterno-mastoid  and  trapezius  mus- 
cles, 269,  270. 

of  tongue,  283. 

Spasmodic  contraction  of  the  hip,  481. 

tabes,  329. 

Speech,  center  of,  32,  86. 

its  alterations  in  Duchcnne's  disease, 

279. 
its  modifications  in  paralytic  dementia, 

281. 

muscles  connected  with,  370. 

Spina  bifida,  its  clinical  relations  to  nerve 

centers,  292. 
Spinal  cord,  287,  288. 

an  organ  of  conduction,  299. 

anterior  and  posterior  root  zones  of, 

297. 

anterior  fundamental  column  of,  297. 

antero-lateral  columns  of,  298,  300. 

appearance  of  transverse  section  of, 

294. 

arrangement  of  its  sensory  fibers,  304. 

arrangement  of  motor  fibers  of,  302. 

as  a  nerve  center,  309, 

automatic  action  of,  304,  312. 

a?sthesodic  system  of,  313. 

central  canal  of,  295,  306. 

central  myelitis  of,  338. 

classification  of  diseases  of,  815. 

clinical  points  pertaining  to,  313, 

columns  of,  290,  291, 

columns  of  Goll  and  Burdach,  297,  809. 


INDEX. 


499 


Spinal  cord,  columns  of  Goll,  Tiirck,  Bur- 
dacb,  their  physiology,  297,  298,  309. 

commissural  fibers  of,  301,  307,  309. 

commissures  of,  290,  296. 

construction    of    anterior    horns    of, 

294. 

decussation  of  sensory  and  motor  fibers 

of,  307,  308. 

degeneration  of  the  cells  of  anterior 

horns  of,  334. 

direct  cerebellar  column  of,  298. 

direct  and  crossed  pyramidal  columns 

of,  297. 

excitability  of,  300,  301. 

fissures  of,  290. 

fibers  of,  general  proportions  of,  309. 

focal  lesions  of,  339. 

focal  lesions  of,  above  lumbar  enlarge- 
ment, 346. 

focal  lesions  at  lumbar  enlargement  of, 

347. 

focal  lesions  of,  cervical  enlargement 

of,  342. 

focal  lesions  of  lateral  half  of,  348. 

focal  lesions  of  mid-dorsal  region  of, 

345. 

focal  lesions  of  upper  cervical  regions 

of,  342. 

functions  of,  299. 

functions  of  its  gray  matter,  300. 

general  construction  of,  289. 

gray  substance  of,  component  parts  of, 

295. 

its  gray  and  white  matter,  294,  295. 

its  investing  fluid,  292. 

kinesodic  system  of,  313. 

membranes  of,  292. 

myelitis  of  anterior  horn,  331. 

nerves  arising  from,  291. 

nerve  cells  of,  302,  303,  304,  305. 

non-systematic   or    focal   lesions    of, 

314,  315,  339. 

paths  of  motor  and  sensory  impulses 

in,  299,  300. 

reflex  action  of,  310. 

sclerosis  of,  lateral  columns  of,  329. 

special  centers  of,  301. 

systematic  lesions  of,  313,  315. 

systematic  lesions  of,  aesthesodic  sys- 
tem of,  315. 
systematic  lesions  of,   kinesodic   sys- 
tem of,  325. 
trophic  function  of,  301. 


Spinal  cord,  white  substance  of,  component 
parts  of,  295. 

varieties  of  fibers  in,  302. 

vaso-motor  centers  of,  310,  311,  351. 

epilepsy,  345. 

hemiplegia,  348,  850. 

Spinal  nerves,  9,  355. 

nerves,  roots  of,  9,  355,  357. 

paralysis,  atrophic,  331. 

Stomach,  center  of  movement  of,  67. 

effects  of  section  of    pneumogastric 

upon,  252. 

Strabismus,  internal,  its  clinical  signifi- 
cance, 146,  149,  176. 

Suture,  coronal,  its  relation  to  the  fissure  of 
Rolando,  68. 

lambdoidal,  its  relation  to  the  external 

paricto-occipital  fissure  of  the  cere- 
brum, 68. 

Sympathetic  nerve,  7. 

communications  of,  9. 

distribution  of,  7. 

function  of,  7. 

cuts  of,  6-8. 

Tactile  sensation,  destruction  of,  49. 
Taste,  anaesthesia  of,  236. 

effect   of  chorda-tympani  nerve   on, 

160. 

effects  of  nerves  upon,  225. 

effects  of  section  of  fifth  nerve  upon, 

160. 

hyperaesthesia  of,  235. 

its  clinical  relations,  235. 

its  relations  to  facial  paralysis,  193. 

its  relations  to  glosso-pharyngeal  nerve, 

224. 

limits  of  its  situation,  226. 

buds,  225,  226. 

Teeth,  chattering  of,  in  spasm,  164. 

grinding  of,  in  spasm,  164. 

Temperature  of  the  body,  its  relations  to 

focal  lesions  of  the  cord,  344. 
Tendo  oculi,  its  function,  121. 
Tenth  cranial  nerve  (see  Nerve,  Pneumogas- 
tric), 236. 
Tetanoid  paraplegia,  329. 
Third  cranial  nerve  (see  Nerve,  Motoroculi), 

127. 
Tic-douloureux,  161. 
Tongue,  fibrillary  tremor  of,  283. 
furring  of,  its  clinical  significance,  1 70, 

224. 


500 


INDEX. 


Tongue,  its  relations  to  deglutition,  227,  229. 

nerves  of,  276,  277. 

paralysis  of,  283. 

spasm  of,  283. 

Trephining,  surgical  rules  for,  73. 
Trigeminus  nerve.  (See  Nerve,  Trigeminus.) 
Trochlear  nerve,  149. 

effect  of  paralysis  of,  150,  151. 

its  origin  and  function,  149,  150. 

Tumors,  cerebral,  their  symptoms,  164. 
Twelfth  cranial  nerve   (see  Nerve,  Hypo- 
glossal), 272. 

Upper  extremity,  motor  centers  of,  42. 
Utricle,  206. 

Vaso-motor  fibers  of  fifth  nerve,  163. 
Vestibule  of  labyrinth,  200,  204. 
Vision,  accommodation  of,  132. 


Vision,  centers  of,  86. 

colored  perceptions  of  objects,  50,  51. 

contraction  of  the  field  of,  49. 

deceptive,  its  clinical  significance,  142. 

determination  of  distance,  140. 

its  abnormalities  and  their  conse- 
quences, 109,  110. 

perception  of  color,  116,  118,  119. 

physiology  of  light  sensations,  115. 

tests  for,  112,  113. 

Visual  purple,  116. 

Voice,  its  relations  to  facial  diplegia,  197. 

nervous  supply  of  muscles  of,  263. 

relations  of  spinal  accessory  nerve  to, 

264. 

Vomiting,  center  of,  67. 

nervous,  258. 

Wrisberg,  nerve  of,  177,  179. 


THE  EHD. 


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8 

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I 


